My parents gave me a great deal of freedom to choose my own reading material and I do the same with my children. If I do not like some of the content of what they are reading, I will talk to them to make sure they are separating the content from their attitudes and behavior. I have never found an issue.

If your values are clear, and demonstrated in the way you live, it is not as confusing to children to learn that others do not share these values as many parents fear. If I am concerned about something in a book, I just ask their opinion of it. They can clearly enjoy a book and empathize with its protagonist - even when they see that the choices they make or the beliefs they have "would not be a good idea in real life".