How many is too many?

This question has been coming up alot in the last few days.....How many people can you sleep with before you are considered a turbo slut?
I mean, normally a guy wouldn't ask you how many people you have slept with, but every once in awhile you come across the one guy that does care. My ex claimed he wouldn't date a girl that slept with enough guys to be in the double didgits. I have friends in their 20's that have slept with only one guy and I know girls that have slept with at least 70 guys. I know girls that are honest about how many guys that have gotten down with and I know some that have a special formula they use to get their numbers down to what they consider "acceptable" (divide by 1/2 and subtract -2).
So, what is the magic number? And should you be judged on your past?
There are some positive factors to women that have been with many sex partners- they are more experienced in bed, nothing surprises them, you probably don't have the weirdest or smallest penis they have ever seen, they genuinely enjoy sex, and they won't judge you on your man-whore ways....but everyone loves to hate the girl that has been with alot of guys. Our society has warped itself into believing that a man that sleeps around is more desireable to the opposite sex and he is socially accepted and rewarded for his promiscuity. BUT, when a woman is honest about her numerous sex partners she is considered to be less of a person and is looked at as dirty. How is this fair?
Why are women supposed to be ashamed of their past while men are expected to be proud of theirs?