The probability that a book will be challenged, banned and/or censored increases exponentially as the book approaches mega-bestseller status.
As a corollary, if a book or series hits mega-bestseller status, somebody somewhere will challenge, ban and/or censor it for one "reason" or another.
Libraries around the country are currently throwing fits about the 50 Shades trilogy. So infuriating. Censorship is wrong. I don't care if you disagree with the views stated in the trilogy. I don't care if you think it's pornographic. I expect my public library to offer reading opportunities, rather than remove them. Public services have no right to selectively and arbitrarily limit reading material like this just because someone somewhere thinks it's icky. "Ewww!" is not a valid argument against anything, from marriage equality to 50 Shades of Grey.