I know most people won't agree with this, but I have a short list which I might expand.
1. Pulp Fiction. I thought it was stupid, just plain stupid.
2. Any movie directed by Kevin Smith except Clerks. I did like that one. The rest of his stuff is unwatchable. Mall Rats, I think it's called is horrible.
3. The only movie I've actually walked out on was Comes a Horseman starring James Caan and Jane Fonda. I have never been so bored in my life.