(Apologies if this thread has been done before, but I haven't really got the time to trawl through hundreds of posts)
Every Simpsons season, even during the golden era (1-5) has had at least one clunker, or rather one that falls well below the standards of most of the rest. Which one would you rate as the worst in each season you've seen, and if you can be bothered, why?
Here are my picks:
S1: There's no Disgrace like Home
Although this episode improves markedly in the last two acts, it is really the first one that virtually wrecks it for me. Homer seems too sanctimonious and hypocritical in trying to turn the Simpsons into a nice loving family when often he's the worst behaved member himself, Marge acts out of character, and the family at the picnic is too sickly sweet and make the Flanders seem exciting in comparison.
S2: Couldn't decide between these two:
The first of many flashback episodes, however, unlike the family-type classics like I Married Marge and Lisa's First Word, and like Homer's Barbershop Quartet we are not sure whether the whole thing really happened. At least that episode is funny because of the way it satirizes so many aspects of the Beatles in the Simpsons context, however, this is just a dull story with Homer making a fool of himself with no long term reward.
Brush with Greatness
I know some people like this, but not me. Far too many plots crammed into a single episode - the family go to Mount Splashmore, Homer tries to lose weight, Bart finds a picture of Ringo Starr in the attic, Marge enrolls in an art class, Burns poses for Marge - what's the episode supposed to be about? The constant close-ups of Homer's obesity and naked Burns are disgusting as well. Oh, and Ringo can't act.
S3 Burns Verkaufen der Kraftwerk
I know Simpsons has never been renowned for its political correctness but I find the German stereotyping not very funny and actually slightly offensive, maybe because I've learnt German and have relatives over there (don't the Austrians wear Lederhosen anyway?). Burns is irritating, but the real problem is Homer is far too stupid even by his standards. He doesn't even remember the name of his own job, he does a jigsaw puzzle to keep himself occupied during the night before an important meeting and doesn't know how to hit the pieces together, his only 'meaningful' contribution when talking about the SNPP is the candy machine. IMO the weaker episodes have almost always been because of Homer's excessive idiocy or the jerkass Homer that has marred much of the later episodes.
S4 Itchy and Scratchy: the Movie
I don't like this much, mainly because I felt Homer and Bart's characters were too exaggerated. Homer tries to take all the credit for Lisa being a grade A student even though his sole contribution towards educating her was apparently to read to her TV guide, gets stuck in the child's desk, doesn't know which one is Itchy. Bart behaves too badly even for himself - he has always had a mischievous streak, but more as fun-loving prankster, than the wilfully rebellious type you see in this episode. The most unbelievable part is how, after letting him get away with numerous offences such as breaking Abe's false teeth, wrecking gramophone records and smearing mustard on the carpet, Homer finally lays down the law and punishes Bart for a comparatively minor one like letting Maggie escape, who emerges unscathed. How many families has there NOT been an incident where their little one has slipped through their fingers unnoticed?
S5 Burns' Heir
There are a few funny moments in this one, but what really ruins this one is again Homer's incredible stupidity. The speech he gives Bart to read out for Burns reads more like from a retarded 4 year old than a dumb but reasonably articulate 36 year old ("Hello, Mr. ...Kurns. I bad want...money now. Me sick"), laughing at Bart being kicked in the butt, mistaking Hans Moleman for Bart and repeatedly kissing him are prime examples. Also Bart trashing Burns' estate, getting to love Burns and rejecting his family - where's the credibility?
S6 Another Simpsons Clip Show
The worst by far, simply because there is no plot to speak of. It's just an excuse for lazy or creatively challenged (or both) writers to show a series of clips, based around a dumb romance theme, many of which are poorly assembled and often far too long.
I can't comment on the subsequent seasons because I haven't watched enough of them yet.