Breja: People seem to have strnage definitions of "bad". I'd never call Monster Squad or Evil Dead "bad". Or Flash Gordon. Campy, sure, but bad? Great music, great cast, some pretty good and unique visuals.
I do love DOA. It's truly one of a kind bonkers, fanservice trash. Me and my friends must have watched it at least five times now? It's absolutely the best for a "pizza & beer" kind of evening. If you like beer. I don't, but pizza & DOA is still good enough for me.
Some of my other favorites would be:
Ninja III - The Domination. The title says it all, right? It's the best example of the kind of crazy, awesome 80s nonsense eveyrone tried to parody for a while a few years back, and no one could really get right, because the original is unbeatable and already funnier and cooler than anything they could come up with.
Lifeforce - ok, so, stay with. It's about naked space vampires from Halley's Comet. Where it gets really awesome is it's not really a "B-movie" in terms of production values. The special effects are actually incredibly good. The music, composed by Henry Mancini and recorder by the London Symphony Orchestra, is just fantastic. It really is an incredible movie, has to be seen to be believed, the kind of trashy plot and great movie-making.
Wolverine Origins - it's terrible, but it is also absolutely hilarious. The terrible CG, the nonsense story with the magic memory-erasing bullet, the "could we get Deadpool more wrong?" part, the part where Wolverine gets taken in by Clark Kent's parents... it was one the most fun movie going experiences I've had.
It's not a concept everyone is familiar with; watching legitimately bad movies for entertainment, realizing that it's funny because a filmmaker failed to do something, like a horror movie where the monsters aren't scary, just funny looking, or something, so they go to the nearest thing they can think of.