I would almost rather see a bad movie than a movie that is potentially great due to a powerful premise but ultimately fails. This is entirely subjective to my own views, of course. But I do know a lot of people that feel this way about certain movies.
I was using the toilet yesterday and I remembered a film that I viewed on Netflix a year or two ago called http://www.youtube.com/watch?v=1HbsHatqKqc. I thought it had massive amounts of potential and one of the most anticlimactic endings I've ever seen. I watched the original made for TV movie, which was mediocre and realistic, but I hadn't read the book which is based on a true story.
I don't remember being that disappointed since the Ninth Gate came out.
Do any movies make you feel this way?