Why would you question the motives of a promiscuous woman, but not a promiscuous man?
God Almighty, need I go through this again?
(1) The average man has no trouble having an orgasm. In fact, in every men's magazine or publication geared towards men, there are many articles on 'How to Delay Your Orgasm For Her Satisfaction'.
(2) The average woman, while she can be multiorgasmic either alone or with a skilled partner, has no guarantee whatsoever of climaxing, especially with someone new and unfamiliar.
(3) Having sex with a fresh girl is exciting for a man. And we never worry about her noticing our wobbly thighs/leg stubble/T-shirt not matching our underpants- we're going to come anyway.
(4) Having sex with a man for the first time, however, even if she knows him well, is usually the cause of much anxiety for a woman, and this, combined with possible male inexperience/incompetence, may cheat her of satisfaction.
In other words, when the average man gets the average girl into bed, his troubles are over, but hers are just beginning, and she knows it.
The simple uncomplicated emotions (about three; eat/sleep/fuck) of the male are as nothing compared to the multicoloured emotional tapestry every woman hauls around with her.
In a long and extraordinarily eventful bachelorhood interspersed with three legal marriages, two divorces, a few live-ins, countless visits to fetish clubs both alone and with a g/f or wife and all the various problems, scars and traumas attendant on such a past, I've had plenty of time and motivation to study this subject both theoretically and practically, and it ain't pretty.
I have met women whose behaviour leaned happily toward the masculine pattern, but this is very rare.
So, unless she can respond in male fashion, what's the point of a woman being promiscuous?