Frankly, slut as I hear it used, and use it myself, is a gender-neutral term and can be applied to males with the same ease as it can be applied to females, where if anything it's harsher on the male because of the traditional useage of the word to describe a female possibly calling their masculinity into question with those who don't use the word the same way.
Which brings me to my other point. The connations the audience attaches are beyond the control of the person using the word, and therefore judging the person actually using the word on what the audience thinks is grossly unfair unless they knew in advance that their audience does not connote the same things to it.
And also, at this point, I should note that the average useage of slut around here is not even necessarily insulting to someone, as the positive connotations mentioned for "player" below have caught up with the word and the implications of calling someone a slut now are almost totally dependent on the tone of voice you were using; I hear it used in an admiring fashion, as compliment about sexual prowess or even one's powers of persuasion, about as often as I hear it used in a derogatory fashion.
In short: Nice try Rian, but no.