The episode where a cast member dies or otherwise suddenly leaves the show and the writers have to scramble to work around their absence or explain their character’s sudden disappearance.
The Rashomon episodes, alias where each character tells how they saw/perceived an event differently from everyone else.
Clip episodes and dream/fantasy sequence episodes are very, VERY close seconds.
Edited to add: And I see that BrainGlutton beat me to the punch on the Rashomon…but still easily my pick for worst episode format.
The episodes where everyone sits around eating meat all day
In the late 90s, it seemed way too many series had an episode where the main character was on a plane and suddenly the pilot was incapacitated. Guess who had to land the plane?? Surely the most ridiculous one was on The Incredible Hulk.
Disclaimer: The only reason I saw all of these silly episodes was because I did a lot of babysitting in college and one of my charges was enamored of these inane shows.
Beyond that, I truly hate the “very special” episodes of anything, followed by the It’s a Wonderful Life/Christmas Carol rehash episodes. And let’s not forget when the underling/less successful of a group has bragged to absent family and/or friends about being rich/successful/the boss, and when said absent individuals come to visit, everyone pretends to go along with the lie and hilarity ensues.
Actually, my favorite episode if the underrated series Men of a Certain Age was exactly an example of this.
I think this plot would be a great choice for a series finale, where just once, an amateur attempting to land a jetliner would have a less successful but more realistic conclusion.
Hey, this gives me a great idea.
I hate it when a character who has died or otherwise vanished suddenly reappears, usually 20 or so episodes later. Either (a) at least one show goes to explains how this was possible, or (b) everyone just goes on as if nothing had happened.
Best examples: the Bobby and Jock Ewing storylines on Dallas.
Funny, that’s actually the episode of “Frasier” I never rewatch. 
Hercules and Xena both actually managed a number of enjoyable clip episodes that were less clip-heavy and had stronger framing devices than usual. There would be a fair amount of original content and not just one clip after another.
That said, late during the run of Xena there was a clip episode that seemed unusually lazy even for a clip episode. Over the years Hercules and Xena had a few episodes set in the present day that revealed that there were in-universe versions of these shows, based loosely on the “historic” figures Hercules and Xena. Hercules got two amusing clip episodes out of this premise, with the supporting cast playing the show’s writers and producers trying to plan the season. However, the Xena episode I’m thinking of had a half-baked framing device that involved a group of modern-day Xena fans attempting to re-create the “historic” Xena by cloning her and then implanting her with “memories” from the TV series. Maybe something fun could have been done with this concept, but the episode worked out to be mostly the fan characters saying “Here are some action clips, let’s watch them!” Then after that batch of clips, another character would say “Oh, but it’s not all about fighting, here are some comedy clips!”
So this was a clip episode that was literally about watching clips. And if they were going to do that, it would have been more fun to either have fans vote on their favorite clips for a “Best of Xena” episode or have the cast, writers, etc., present their favorite clips.
Didn’t the daytime soaps do this as a matter of course - bringing back ‘dead’ or otherwise permanently-gone characters, sometimes as their own “evil twin” - or swap actors with the old plastic-surgery gag? That’s not single episode things but I think it’s close kin with what Dallas did.
Ugh, yes. Coupling is probably the only show I’ve seen do one of those reasonably well.
My least favorite types of episodes are related: non-geek main characters have to investigate geek-related things, complete with tired stereotype jokes and general culture misrepresentation, or the characters somehow get trapped in a video game! Oh no!
Another that doesn’t show up in too many shows, but is still frustrating to watch, are the episodes with two characters that are very close and have been around or worked with each other long-term, but one of them has been possessed by some supernatural being! They act oddly the entire episode, the personality shift is sudden and coincides with investigating a hinky probably-haunted place, it’s probably happened before (I’m looking at you, X-files), but the other person invariably doesn’t realize something is wrong. Mulder! Scully! Have a fucking code word so you know the other person is really themselves!
Meh. Done well, every one of these types of episodes can be good to excellent. The episodes I don’t like are the poorly-written ones.
If the possessing entity has access to the possessed’s memories – and how can it hide its presence in the possessed if it doesn’t? – then it has access to the code word.
Could be, but the entity frequently doesn’t seem to have access to the memories, or at least all of them. It’s part of why the character acts so oddly. There is also the body-snatcher variety of episode where there would be no potential knowledge gained from memories.
Either way the episodes always play out the same way.
The Rashomon episode of Gilligan’s Island was pretty good.
Or, at least, that’s how I remember it.
Thus setting up a reboot of Lost. “Hey, we survived! Sweet!”
Those poor people. 
If Scully wasn’t tipped off by “Mulder” about to stick his tongue down her throat…I don’t think anything will help. (This being well before they shipped…schlepped…whatever)
Besides Mulder was always doing something that would lead one to believe he was a Pod Person.
I’m sure they did, but there was only one daytime soap I ever watched, Love Is a Many Splendored Thing (remember that one?), mostly because Donna Mills was in it. :o
I was thinking of prime-time shows; I think Dynasty did the same thing with Emma Samms (Drool!!! :o :o :o), but I was watching that series with my ex about ten years after the fact, so I don’t remember how it played out.