Some old episodes look like more burlesque movies from the same period than what looks Simpson-like to me. If I remember well, there is an episode where a pet is shown to a chain smoker veterinarian woman (I think), and the veterinarian takes a puff in the middle of the phrase she pronounces. To me, it doesn't sound Simpson-like to me. Plus, I don't find it funny at all. The same can also be said for Homer's hammy line about Maude actually being alive in Bart of darkness. Also, among the 4 Jean-Reiss 1995-produced (but aired between 1997 and 1998) episodes, only Lisa's sax looks the most Simpson-like to me. The other 3 have scenes that don't make me think I am watching The Simpsons:
The Simpsons Files looked already weird before the X-Files crossover began, like for example Leonard Nimoy's monologue that makes him look like some TV horror movie host, the characters saying the same thing at the beginning, or Homer's whole weird adventure in the forest (the Psycho music he is hearing being actually an orchestra, the talking frogs, Abraham bursting out of the bushes and Homer writing his scream), unless this scene is itself an X-Files reference (given that I didn't watch this serial, maybe it's a reference, but if it isn't, then I don't understand why is Homer's whole adventure in the forest so weird). Actually, when the crossover began, the episode started to look more Simpson-like to me.
I already said why I consider the Shary Bobbins episode the worst Simpsons episode ever: Shary's presence causing the characters to act out-of-character and the fact that it looked like the episode was too busy on parodying Mary Poppins that the show forgot to be itself, along with the characters.
Homer's plot from Simpson tide: to me, it looked far more like a burlesque movie from the period the episode was produced than a Simpsons plot. I don't understand why his plot is like that (the instructor, the graduation scene, Barney's mother talking about her son sleeping, or the whole submarine part; listing all the non-Simpson-like scenes from this same part would take a long time). While I can understand why G.I. (annoyed grunt) can be hated, Homer's plot looks far more Simpson-like to me (the Looney Tunes reference scene is really short, and outside of this scene, it's just a normal Simpsons episode to me).