Looking back at "Homer's Enemy", while some believe it was the gateway to Jerkass Homer, another thing it has in common with the Scully era is also characters acting out of character to make parts of it "work" (Lovejoy, Marge, and Lisa laughing"s at Homer dozing off, Mr. Burns being swayed and hiring employees out of pity, Smithers being right there and not even attempting to stop Grimes from reaching for the high voltage wires), plus it may have been the start of Moe becoming violent, somewhat shits on Simpsons history (Homer did not win the Grammy by being lazy), and a blatant continuity error within the same episode (the news shows Grimes living in a small house, then suddenly he says he lives in room between two bowling alleys) as well as a character who seemingly teleported (Chief Wiggum should be in the audience, but Sarah Wiggum is right there with Clancy nowhere to be seen).
"Secrets of a Successful Marriage" could be an early Jean episode, since as I've said, it basically flat-out says that Marge is an enabler who will always take Homer back no matter how much he screws up, plus the start of Stalker Moe.