Had some trouble getting through Brisingr, because I read all 3 books back to back and the complete lack of anything original was beginning to outweigh the guilty pleasure I get from their badness.
The same with A Dance of Dragons, although not nearly as much as Feast for Crows. I really hope those 2 are just that way due to being the middle-point of a long series.
And Twilight.
It may be that everything I heard about it before I picked it up influenced me, but when i started reading it, I found Bella's viewpoint drowning in so much whiny teenage angst that I threw the book against the wall after about 20 pages.
EDIT:
There was also one we had to read for English at school (I'm Dutch, so pretty much all books we need to read for English are 70-page heaps of Meh, this one was different.) that was apparently the life story of some Irish-American that immigrated to Ireland. it lacked most sorts of proper punctuation, was written in the most boring way possible, and managed to make me yawn during a part where the protagonist's baby brother died.
Also the Bible, although I will freely admit that that is probably due to me not being very open to Religion. Still, I tried.