Why is sex supposed to be free? It never is. Ask anyone. Like Sebastian Horsley, England’s low-rent Oscar Wilde. “The difference between sex for money and sex for free,” he writes, “is that sex for money always costs a lot less.” Money is the elephant in every bedroom, making your parents’ constant presence look positively bourgeois.

http://www.nytimes.com/2009/08/23/books/review/Bentley-t.html?_r=1&8bu&emc=bua1