Professor Beef
Banned
I honestly don't get the Grimes episode hatred.
They touched on it in the DVD commentary. Some people believe that Homer was being unnecessarily mean and nasty to Grimes, while others just felt that it was just Homer, but turned up to 11. Depending on how you view Homer in that episode, you'll either love it or hate it.
Personally I love it, and it's one of my favorite episodes. I don't think he was being very mean at all, and it was clearly shown that he wanted to be friends with Grimes, or at least get Grimes to like him.