In Malcolm X's biography he tells stories of growing up in Harlem.  A lot of prostitutes worked in his area of town and he befriended many. The prostitutes would tell him that most of their clients are middle-age, well-off men - many with highly prestigious jobs. They mention that many of their clients visited them because their wives were not very pleasant and would withhold sexual contact from them. For many clients, they didn't think the sex was the main reason for visiting. Many of the men just wanted to talk with a woman that wouldn't result in an argument.<p>I remember reading one prostitute telling him directly that if wives had sex with their husbands regularly, they would be out of a job.