Why do I feel like I always have to give this lecture. There is a double standard because it really is different for guys and girls.
A guy can hold up a sign on the corner that says free sex and how many people will he attract? Very few if any at all.
A girl can hold up a sign on the corner that says free sex and how many people will she attract? A lot, unless she is butt ugly.
This is why when a girl sleeps around people say she is a slut/hoe because she's making herself easy. If a guy sleeps around he actually has to go out and find girls willing to sleep with him, so as easy as he wants to be no one is just going to hop into bed with him.