Did anybody notice that Egon's glasses never fit him in Real Ghostbusters. He never bothered to get ones that actually fit. They were always below his eyes. You would always see him moving them. I wonder why the writers did this?

That's what mine do. Nothing I can do about it, it has to do with the shape of my head and nose. And since my prescription isn't very strong I don't really notice unless my eyes are tired.

Anyway, in regards to Egon though, it was probably done to drive home Egon's nerdy and awkward character traits (the nerd pushing up his glasses is a pretty classic gesture).

Additionally, Egon is fairly stoic, but using the glasses as a prop the animators could depict several different emotions without actually making Egon emote facially.

It can also be used as a subtly sarcastic gesture, too.