There's a special kind of person on internet dating sites who isn't just there to find love (or sex), but who wants to work out their Ann Landers fantasies on unsuspecting users. That is, instead of just sending or responding to a message, they send advice. Lots of advice, about what's wrong with your profile, about how your message was insufficient, about how your picture is bad.
Now don't get me wrong -- clearly, I enjoy criticizing online dating messages and profiles more than the average bird. I understand the impulse to respond to a person's message with an explanation of what they're doing wrong, because so many people do so many things wrong. But responding directly to a profile with unsolicited criticism (unless they've done something totally offensive, in which case, hate on haters) is just plain rude.