The rationale is that there would be very, very few guys that would actually like me for how I am, and out of that there's only a fraction that I would actually like back. Therefore, the chances of a guy who is hitting on me being one of those people (instead of either a guy looking for someone 'easy' or a guy who does not see women very often and goes, 'hehe, female, hehe' because of an uncontrolled primitive instinct) is very, very, very, very, very, very, very, very, very low. In fact, the chances of it happening are negligible.
So guys, stop it. I'll come to you.