Can't necessarily judge a man or woman by the number of partners they've had. I'd look more for clues like numbers on bathroom walls, the number of persons in the room who snicker when you announce you are dating this person, etc.
That's what I've learned anyway. I've dated several people. Except for one, there was no corolation between # of partners and how they treated me. And the one was a man-ho, but as it was dating, not bf/gf, I let it go. He was cute.
And because I spent a lot of time hanging with the guys, I knew which girls caused the collective snicker...ironically I knew some who had been around the block twice as many times...but were discrete...and still dateable.