Another thing: western culture, especially American culture, promotes extroverts and outgoing people in general. If you're outgoing, you're a hero. If you're an introvert, you need to be fixed (something is wrong with you). So if you have a sleazy guy making first move, he thinks(perhaps subconsciously) he's behaving the way the society expects of him. At some point he is either too horny or too stupid to know what's happening around him. Which is still wrong, of course.