Hard to say actually....most paysites catering to men don't gather demographic info from their members when they sign up -- like sex. Most don't even have little surveys running to gather that info...
In most cases, the only way to tell is by the name of the CC holder that's joined. Even then you can't claim that it's solo women that are joining -- you've got couples and the ever-elusive bf/husband/roommate/son who uses their gf/wife/roommate/mom's CC to sign up....
