I heard John Moore interviewing Victor Malarek on CFRB radio in Toronto.  Malarek describes the men as coming from all walks of life.  Many of the men are not those who one would think as lonely depressed individuals who can't get a date.  Quite a few are "happily" married.  He mentioned men who have wives whom they treat with respect (not including the cheatin').  Essentially, these men would not ask their wives to perform certain sex acts; they would ask/demand prostitutes to perform those same sex acts.  There are men who prefer getting prostitutes because those men had bad relationships with women.  Malarek described these men as being dangerous to the women.

Malarek's focus was on the men who look for sex.  It will be interesting reading his book.  I'm guessing that he will have a show on the same topic.