So, Alice and Nate got talking and... 
The question is, why do the worst episodes?  In poring through the entire catalog of "Supernatural," we found it way easier to come up with a worst list than a best one.  That and Alice also went through old articles and found her most viewed article ever was her Ten Worst Supernatural Episodes list from back in 2012!  There have been MANY bad episodes since then so it was time for an update.  Nate was all too eager to join in on the fun.  
Today is part one, or episodes 6-10 on each author's list.  In a few days, we'll cover episodes 1-5.  
Nate’s Choices
This is harder than I expected.  Oh not because I think the show is always wonderful - after well over 200 episodes, some are just not going to be as good as others.  At other times, I find myself disliking a storyline or character arc, which was over several episodes - should I count all of them?  So let me explain my method for selecting these ten.
I had to remember the episode.  More than a few episodes I would rank as bad, but ultimately so forgettable they’re not even worth bringing up again (this is my opinion on episode 8.15 “man’s best friends…” - it’s not good, and barely memorable).
Related to the above, I personally count faults against the canon and worldbuilding more than most.  A bad monster of the week episode - well you can skip it in a rewatch and not miss anything, we can all pretend it never happened.  This also helps cover up bad moments of character.  But a bad arc episode?  Momentous events which are supposed to impact our characters?  Well those ruin episodes that come after it and I find extra guilty.They invoked feelings of distaste and are poorly executed.  It wasn’t enough to just make me hate it.  For example, I personally hated the death of Bobby - but I can’t argue that it wasn’t very well executed and handled well in story.  The show wanted me to hate that death and it succeeded.  So to make this list, an episode also had to fail at what it wanted to do.
So without further ado, in an order that will probably be different tomorrow..
10 - "Red Sky at Morning" (3.06)
This will be my one exception to the above listed rules - and part of that is just because I can’t tell you off the top of my head what happened in it.  The only saving grace in this episode is Lauren Cohen in a fetching dress (and Dean in a tux if that’s your preference) as well as the first mention of Castiel. Yes it’s true!  If you listen to the ritual the boys say at the end, Castiel’s name is invoked during it.  Otherwise this episode is just a mess, narratively and the characters don’t seem to know what they want.  The shame of it is that I really liked the idea of Bella and think she could have been a great catwoman to Dean’s batman.  But this episode is the best example of how much trouble they had with her execution
9 - "Rock and a Hard Place" (9.08)
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Just an episode made up of sheer cringe and while it doesn’t impact the season arc much, I am docking it for what it did to character arcs.  Dean had a whole thing about not wanting to torture again in S4.  In S9 most of his troubles arose from breaking his conscience and sticking Gadreel in Sam.  More than most anyone, Dean should know about having a personal moral code and not breaking it.  Yet in this episode he just casually tosses that all aside to get with a favorite porn actress.  Early show Dean - I could see this fitting in with his character, but by now?  After all the character is supposed to have gone through?  No.  To make it worse, this could have been a chance to show a side of Dean that we don’t see often, one that is understanding towards others, even a little sweet, and not just a horndog.  Just imagine the episode had we gotten to see Dean intimate with someone emotionally instead of physically.  Instead of a chance to grow and develop the character, this episode has the show just flanderize him.
8 -  "LOTUS" (12.08)
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The president being satan is certainly an evergreen option for any show, as the fans of the party opposite of whatever president happens to be in the white house will already think that of him/her.  So when you have a set up threatening to drag down the show into petty politics which are beneath it, you better make damn sure that the payoff is worth it. (pun intended)  So what was the point?  What was the payoff?  Was it all to make a kid?  Lucifer’s previous vessel was a literal rock star with numerous women fawning over him - he could have spawned an entire baseball team of nephilim without any suspicion.  Was it to give the boys a challenge?  They reach the president and save him in the very same episode.  To toss them in jail?  Again, they’re out of supermax prison by the next episode.  No real stakes, no real consequences.  Then in the following season, the show says that wasn’t even the president!  So we mucked around with SPN’s world-building for… what, a one off joke?  This is just pathetic.
7 - "Bring 'em Back Alive" (13.18)
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I honestly debated between this one and LOTUS, as they’re almost a tie.  So what’s up with this one?  First of all, we have Dean & Ketch on a magical journey that accomplishes… nothing.  Zero.  Zip.  The entire effort could have happened off screen and then be referenced in a throwaway line for all the difference it made.  Second of all, we have a retcon of Gabriel’s death in S5.  A moment in the show that was amazing and had great impact on the audience as it culminated a powerful character arc, was now cheapened.  And it made no sense within the canon of the show!  To top it all off, there was a simpler solution in the middle of it: Have Dean & Ketch rescue the other world’s Gabriel.  Then this episode would have actual weight!  Things would pay off and go in interesting directions.  Instead this was just an episode absolutely wasting my time, meaning it is just slightly worse than LOTUS.
6 - "The Things We Left Behind" (10.09)
I’ll admit, my tastes may run a little counter to some of the SPN fandom - and that’s ok.  Part of this is that I actually like the concepts of Bela and Claire.  Emphasis on the IDEA of them, even if I have to admit that their executions were so often lackluster.  So in a lot of ways I probably hate this episode more than even Claire haters as it had the job of bringing in a great source of potential drama and character examination into the show, and failed.  This gets even worse because by now the show seemed stuck in a rut and could have used Claire to take it in the new directions that Jack would do several seasons later.  Not to mention this is one of the few episodes that made an effort to give John Winchester some redeeming qualities after Jeffrey Dean Morgan left the show.  On paper I have ever reason to love this episode, but it’s all just so… bleak and poorly executed it damn near makes me weep for what could have been.  If I ever do another SPN fanfic, it may have to be on a “fix” of this episode.
(Coming up on page 2 - Alice's choices!) 

Alice's Choices
My criteria for picking bad episodes is a mixture of a couple of things.  One, is it one of the more critically panned episodes?  Something so bad, that even when it's good it's still really bad?  Two, was I extraordinarily pissed after watching, cursing to the high heavens that yet another of my very precious hours was ruined by a spectacular lack of foresight by the creative team?  Many episdoes actually hit that list, so then I pared it down to, "Which ones were bad on an extraordinarily epic scale?"  Now we have winners, or should I say losers!  
10 - "Bugs" (1.08)
I know, it’s season one, right when "Supernatural" was still trying to find it's footing, but how can this not make the “worst” list?  It’s legendary in it’s badness.  So many things were not done again after “Bugs” was done.  For one, Sam and Dean were banned from using umbrellas again.  Bad and tacky special effects weren’t used again as a substitute for a climactic battle until the season closer in season 13.  We certainly haven’t had a monologuing Native American since then.  At least the showdown with the bees in the attic that was supposed to take all evening but only lasted a few minutes led to many great behind the scenes stories.  It was an idea that writer Eric Kripke was warned couldn’t be done, and dammit his producers were right.  But when this horrific family ordeal, ending with a very shaken family, closed out with the brothers cruising off in the Impala to the hard rocking tune of “There’s No One Like You” by the Scorpions, you knew at that point the post production team had given up. 
9 - "Route 666" (1.11)
I get it again, season one was an uneven season, but a RACIST TRUCK?  Seriously?  It’s interesting that Brad Buckner and Eugenie Ross Leming have continued to deliver scripts since then that have been very tone deaf with racist and misogynistic plots.  It’s really a shame to see this was only the beginning.  Check out bad the dialogue and hammy acting in this one though.  Easily one of the series worst in those categories.  This only ranks low on this list because season 1 gets a rookie pass.   
8 - "Mannequin 3: The Reckoning" (6.14)
I usually hate poorly done, ill-conceived, absolutely stupid monster of the week episodes when they immediately follow something far better that ended with an exciting mini cliffie.  Case in point, “Mannequin 3: The Reckoning.”  It was the episode to follow that explosive ending of the brilliant “Unforgiven,” in which Sam is left seizing on the floor after being flooded by traumatic memories of his torture in Hell.  After freaking about about poor Sam for a week, horrified by the instability in his head, it was all brushed under the rug in 1 minute so we could endure 42 more minutes of a super-bad killer doll story.  Talk about a massive letdown.  This was a disappointment that was repeated again in season seven”s “The Girl Next Door” after Sam’s heartbreaking meltdown and the brothers both being rushed to the hospital in dire straits in “Hello Cruel World,” and season eleven’s “All in the Family” after the dramatic and fan thrilling ending of “Don’t Call Me Shurley” (They STILL haven’t acknowledged the amulet?). 
It’s all a glaring reminder that when lazy writing happens, huge and memorable opportunities are lost and the resentment truly never ends comes re-watch time.  But of all these examples, “Mannequin 3:  The Reckoning” was the one in the poorest of taste.  I just don't know what they were thinking when breaking this one.  
7 - "There’s Something About Mary" (12.21)
This could have easily been, “The British Invasion” as well.  Both were equally asinine in their plotting, had ill conceived ideas that came out of nowhere (the evil headmaster?) instead of being developed organically, and plotting, dialogue, and editing were just plain awful.  The fact that a Harry Potter ripoff where the students have to kill each other from “The British Invasion” didn’t make the list just shows how bad “There’s Something About Mary” is.  That’s because yet another strong female character, Eileen, is killed for no good reason other than to get a cheap emotional reaction from Sam, which was mild at best.  By season 12, killing good characters for no good reason had turned into lazy desperate writing falling back on the same tired trope. In other words, it had gotten really annoying.  It was enough to trigger #firebuckleming outrage on Twitter and rightfully so. 
I think history has proven that the whole British Men of Letters story was an utter pile of junk and a total waste of time in season 12, easily rendering that season one of the worst of the series.  This episode was the BMOL at their dastardly peak, even though it was never clearly explained why they were that way and what their true mission was.  They were not believable villains and this mind programming on Mary Winchester so she could kill all the American hunters, including her OWN SONS, made no sense whatsoever.  The showdown in the bunker was a pile of junk, but at least it did lead to something promising in the next episode.  Add onto this the whole weak Lucifer and Crowley scene killing pissing contest in the fake Hell lair that had already dragged on for episodes and I just wanted that hour of my life back so badly.  Actually, three hours, since I spent two hours on Twitter afterward bitching up a storm about this episode. 
6 - "Man’s Best Friend With Benefits" (8.15)
Not in the history of “Supernatural” has a more tone deaf episode aired.  Not even “Route 666” although it might be not coincidence that both episodes were written but the same writers.  A black woman is a familiar to a white male witch.  That woman splits her time between her human form and animal form, a dog.  This of course requires her to wear a dog collar.  Oh, and she’s his lover.  So basically we’ve got a black woman acting as a sex toy to a white man while wearing a dog collar and calling him “master”.  If that sounds offensive, just watch the rest of the plot.  It totally butchered all existing lore on witchcraft, forgot completely the strides the brothers made toward healing their rift in episodes prior, was boring and sluggish as hell and the dialogue was perplexing at best.  Even the usually strong VFX was B-movie quality.  Considering that the episodes previously introduced the most exciting Men of Letters legacy and the MOL bunker, this was just a complete letdown to anyone who thought they might actually keep running with that.  It was like it never happened. 
Coming soon, episodes 1-5!  Agree with the choices so far?