For example:
*In Married...With Children, Al always using the toilet and his feet smelling seemed to go away around Season 7 or 8.

*The Simpsons used to do cutaways to some unrelated joke, they claim the stopped when Family Guy made it a staple, but they really only did it for a couple seasons and stopped years before Family Guy was on air. There's also Bart's prank calls that just ran out (likely in part due to the rise of caller ID) and Principal Skinner's 'nam flashbacks.

*Invention Exchange on MST3K - this was due to Mike not being as inclined in that department as Joel. They tried it for a short while, then it fizzled.

*Hal's hairy back in Malcolm In The Middle.

*Killing Kenny in South Park.

One running gag from M*A*S*H that I hate was Hawkeye's jokes about Radar's alleged lack of personal hygiene. It didn't go away though until Radar left, since Hawkeye had one more joke in "Goodbye, Radar", where he commented that Radar should be allowed to take a shower immediately when he returned from R&R since he actually "wanted" to take one.

M.A.S.H. ended it's original run when I was 14 years old. And I was a big fan of the show. I honestly don't remember there being a running joke about Radar's hygiene or lack of it. But there was the running joke about Radar being uncomfortable with any kind of nudity. Being seen naked or seeing anybody else naked.

Ed.