umm.. movies which make you depressed, miserable, and sleepless are GOOD. Whether or not you enjoy the experience may inform your decision to see them again or buy the DVD, but really has no role in any discussion of whether or not they "suck" - to put it eloquently. And if someone buys Requiem for the sake of seeing a certain actress in a state of undress (among other states) they're probably watching it for the wrong reason and will get little out of it.
I'd add, in addition to Happiness and Affliction, The Sweet Hereafter, The Ice Storm, and The Virgin Suicides. As films that the popcorn crowd will find disappointing.