Too hard. I've seen so many good movies that if I tried to make a list it would be too long, and then I'd have to keep coming back to add things when I remembered them.

Man, you don't know what you're missing. Their films are classics. Just need to remember that their films aren't serious. Also, expect to see some cast members you wouldn't expect

I like some Troma stuff. Some is a bit tedious for me when it starts meandering away from clever and toward obvious humor and audience pandering. I'm really glad people like them exist, though. For some reason I really got a kick out of http://www.imdb.com/title/tt0083934/, although I haven't seen it in over a decade.
The only movies I can think of that has ever left me literally awe-struck as the credits rolled are The Devil's Rejects and Jacob's Ladder. I should be able to come up with more later.
Jacob's Ladder was a solid film. I didn't really like The Devil's Rejects, though. I liked House of 1000 Corpses a lot more.
