Call Girls Out-Class Mistresses
A mistress is fundamentally riskier than a call girl because her idea of one-upmanship is getting the man in trouble with his wife or primary partner, to break up his main relationship. This wasn't as likely in the good old days, when mistresses and prostitutes had more in common--but Jamie and Jaimee are modern women. These are not your grandfather's mistresses. That's why, perhaps, they feel entitled to sell their stories to the tabloids.
A call girl's idea of one-upmanship--which is far more beneficial to the men she sees--is being more discreet than the next girl. If she does a better job of protecting her customer's marriage than anyone else, that's a point of professional pride.