I have always enjoyed good negative book reviews. Either I agree with them and they're fun to read, or I disagree with them and then I have to get the book in question to see for myself. Either way it's a win-win.
For whatever reason, I haven't been finding a lot of nonfiction I love to hate lately (it doesn't help that I barely have time to read nonfiction I'm enjoying). But I did come across this article the other day, in which a reviewer let loose on a personal finance book that they called the "worst personal finance book ever." Go check it out!