The greatest single indicator is she has been living on her own or not, and if so for how long, a girl with her own place can do as she pleases which includes bringing back strangers to bang, I guess in most cases in the US you have to move out for college but where I live it's not unusual for girls as old as 25 to attend local schools or to be on the job market and still live with their parents (which partially prevents sluttiness)
If a girl has been living on her own since she was 18-20, I just assume she's been on the cock carrousel and adjust my game from there
If a girl has been living on her own since she was 18-20, I just assume she's been on the cock carrousel and adjust my game from there