What determines sluttiness? Is it number of partners, or the number of sex acts, or the kind of sex, or whether you enjoy it, or what other people infer about your self-esteem based on what they assume about your sex life? It's all of the above, or none of the above. Either way, you lose.
. . . If you try to argue that you're not a slut, you're implicitly buying into the idea that there are sluts out there. If there's some criterion that will set you free, that standard will indict someone else--someone with a higher "number," or shorter skirt, or a later curfew. So we get bogged down in slut/non-slut border skirmishes over a line nobody should have tried to draw in the first place, and we all lose.
The only "refutation" is to laugh in your accuser's face and get on with your life, however you choose to live it. That's what Slut Walk is about.