What are some episodes you can't stand (apart from newer ones obviously)

I never really rated Marge Be Not Proud.

The plot wasn't particularly interesting. Bart stole a game, everybody was angry at him and thought he'd gone too far, then they made up. And I don't really remember any of it being in any way amusing.

I never liked those Halloween episodes, even going back to the old days.

I thought the episode where Troy McClure married Selma was dull (outside of the “Dr Siess” song!). Because Troy McClure and Selma don’t have enough comedic value to serve as the main figure of an entire episode.

I was not too big on "Krusty Gets Cancelled", I thought it was a weak way to end Season 4 (which is IMO the best season of The Simpsons).

Some of the musical episodes are quite boring.

I had been watching from the older seasons and one I didn't care for was the one from Season 3 where Homer decides not to go to church anymore. Just didn't find it as funny or enjoyable as some of the others. There's also the one from Season 2 where Bart and Lisa try finding either Patty or Selma (can't remember which is which) a boyfriend and in the end they can't find the right guy for her to be with. That one was also meh.

Have you bothered watching the latest seasons? They're pretty damned good.

There was a phase in the back half of the seventh season where it got a little too dry for me as a kid and some of these (e.g. Bart the Fink, Lisa the Iconaclast) are still not my favourites.

I think the second half of Homerpalooza is pretty bad. Might have been the start of celebrity guest appearances on the show being really cringe-inducing.

I was never that bothered by the ones that involve baseball, or American football, or any other American sport, simply because I do not care for American sports. Funnily enough one of the first times I realised the show was going downhill was during a sport-related episode, when Homer and co. go to the Super Bowl. I noticed how lazy the celebrity inclusions had become. They randomly shoehorned Dolly Parton, and I think Vincent Price, just for cheap laughs.