Originally Posted by ultramarina
This. Of course, one can go too far in the other direction, but I'd never consider "I hated this book" to be too far. "I hated this book and anyone who likes it is an idiot"--that is too far.
People like to think that they have good taste, and saying that a book stinks will be viewed by some people who like the book as a criticism of them, even if you do not directly call them idiots. OTOH, a expressing a negative opinion of a books could start a discussion where other people learn about its flaws or where the original critic comes to a new appreciation of the book. One needs to make one's point strongly enough that people actually get the message but not so strongly that they view it as a personal attack and immediately discount it.