I think they are based on a romanticization of certain types we meet in real life. I know my main character was loosely based on several ex-girlfriends of mine, and had a bit of my own inner wild woman in her as well.

I think we all want to speculate about the lives of those with sexual power, becuase that seems intriguing. But they also usually have vulnerabilities (to the point of emotional unstableness in some cases) to seem realistic.