Use of the word "whore" implies a staggering depth of societal sexism. So does "slut". These words represent a concept of sexual inequality that is so completely embedded in our culture that a lot of apparently normal people use them without realizing they are revealing themselves to be sexist. What are our words for guys who act like whores and sluts?
"Sowing his wild oats", with a nod and a wink. Smooth talker, Don Juan, over-sexed. About as negative as it gets is womanizer and skirt chaser. Compare to wanton, fast, loose, easy, pushover, wild. And nymphomaniac, as if being sexually active is a disease, but only if you're a woman.
Maybe it's just jealousy on the part of men, who would love to be able to have sex as often as women can. A centuries-long case of sour grapes? Actually, we seem to have medieval concepts of ownership combined with Victorian shame informing our sexual identities. It's embarrassingly antiquated and unconscious. And completely sexist.