Well if you go only on the movies, the guys only saved the world twice. This of course made them heroes, but not super heroes. Besides that, they are normal guys who perform a service, like carept cleaners, except they investigate and “clean up” ghosts. To me the major appeal is that they are completely normal guys who are doing an unusual job. A SuperHero to me has certain characteristics that make them some what virtuous, moral, etc. The GB's are good people, but not overly moral the way Superman may be, they drink beer, smoke, swear on ocassion, and hit on women (I'm describing things for all the guys, I know Egon doesn't hit on women the way Peter does). My point is that they are heroes the way fire fighters and police are heroes in times of disaster (9/11), other than that, normal guys, just like you and me.