Diverse tastes between books

I'm curious as to what fans out there consider the most annoying criticisms or critics of fantasy books. Why? If you deal with fans of anything, there's a lot of passion and opinion, but how often do you try to have a serious discussion with supposed 'fans' of something, only to find out that most of their opinion has nothing to do with liking the subject and more to do with being critical of it? I have had discussions where I wondered why they bothered reading anything, since it didn't seem to be anything they enjoyed. I'm left shaking my head, wondering where it all went wrong for them.

As you can tell, my pet peeve are people who have standards or expectations that exceed the point where anything beyond a fraction of available content is likely to please them. Then I read one of the three books (out of thousands) they liked, and it's nothing special. If anything, it lowered my enjoyment of it because of all the connotations.

I can enjoy a flawed work for what it is. Maybe I am just missing the snob gene or something.