See, my scale of "excellence", for anything really, not just films, is something I call "replayability", or the subject's overall ability to withstand multiple viewings without depreciating significantly in value, or enjoyment experience. This might not be my perfect list to comment upon because "great" films, no matter if I find them too sappy, scary or sad, I'd always want to view again to revisit those elicited emotions.
That said, I'll add a few films that I've watched once, and would never want to watch again, because as they say,
"once is enough".
The Descent - I cheated on this film, and watched it agian, but still, I liked it, but not enough to want to view it again (ever).
Requiem - too normal and too "real" of a portrayal of exorcism (I didn't even know the girl was possessed until halfway through the film) to subject myself to again.
The Saddest Music in the World - I know, I know. It's not really a "painfully, emotional" film, even though that's what the story would lead you to believe. The only reason I'm commenting on this film is that it was literrally too painful for my mind to comprehend what was going on, and how I basically viewed it as a "parody" film (whether or not it was meant to be portrayed as such I don't even care to find out). I really disliked sitting through the entire thing.