I wrote a book on non-fiction essays called The NSFW Files: An Appreciation of the Erotic in Literature and Comics at the Chicago Center for Literature and Photography. These posts offer additional looks at dirty books.
Originally published in 2005, Feral House has reissued Sin-a-Rama: Sleaze Sex Paperbacks of the Sixties in a new, expanded edition. Edited by Adam Parfrey and B. Astrid Daley, Sin-a-Rama delves into this lesser known literary genre.