I read what I like for the most part. For years I would only read certain authors (like King) because I was sure I would like the book. In the last decade I've tried to branch out and been burned several times. I have figured our a formula but I think in the end people just read what they like and that has a lot to do with how it is written.
Some authors can write a subject I'm totally interested in (like smut) very badly and turn me off while others can do something I am on the fence about (like cathedral building) very well and produce one of my favorite books ever.
As far as the original question...I am passionate about books but don't really get that worked up about anything. Maybe it's the medication.
I also think "50 Shades" shows most women love some crazy semi-rough sex weather they want to admit it or not.