The exceptions to the rule are where the writer/star/director is aware of their own ridiculousness - see also Curb Your Enthusiasm.

I haven't seen The Room, but the ne plus ultra of that kind of self-indulgence for me is Garden State. 90 minutes of Zach Braff's daddy issues and romantic wish fulfilment - I've had better afternoons. (It amazes me that it picked up an audience more or less on the basis of having The Shins on the soundtrack.)

The Star Wars prequels fall into that category, even if Lucas isn't in them. Proves very well that he should be shot on sight if ever he approaches a typewriter again. Not a fanboy of the first films by any measure, but at least Lawrence Kasdan or whoever can string a couple of lines together. Left to his own devices, Lucas is capable only of bloated, soulless tech demos.