I'm going with P-Man, in that most guys want to know if the woman they're with has had sex with anyone he'll be running into in his normal course of events.
Nobody wants to show a picture of his new sweetheart around at the sports bar and have them say, "Oh, we had her." or "I've got a video of her."
So if her former lovers remain faceless strangers it doesn't(shouldn't) matter.
In the same vein, I doubt many women want a guy that's screwed all her girlfriends.
