I've actually worked in the adult industry (I work at a production company) for 10 years, and I've read a lot of books and articles about it. I think this book is the one I enjoyed the most.
It offers insights into the personal lives of some of the legends and stars of the adult industry. While it does go into some of the downfalls (drugs, social stigmas, etc), it does so in a realistic manner, rather than a sensationalistic way that modern media is SO apt to do with this subject.
(For what it's worth, I've also read The Other Hollywood, and I know a lot of the people who were interviewed in it, and a lot of them say that their stories and words were twisted around severely.)
So if you want a realistic view of a business that holds a lot of mystery, you might want to give this X Factory one a try.