I think you could be right. But I dont think it means that we only should approach women who give us that body language. I think the moral of the book is to be more conscious about the girls around you, and the people around you. So you could actually see that girl that seem to be attracted to you and then approach.

But I believe you'd trap yourself this way of getting further towards success with women. You might not either sense that the woman likes you nor you might not even notice her at all. Maybe you seem that no one wants to flirt with you and you might question yourself. And there is your first ticket to killing your confidence. You'll have to believe in yourself and be proud of who you are to gain confidence. Confidence is everything when it comes to pickup and approaching.

That's why I believe you should approach multiple girls every day, that way new girls that haven't noticed you start notice you and you'll progress to get more confident. Its not easy to approach a girl, but it's hell easy to waste time and wait for that perfect girl to flirt with you. Every girl in the world haven't noticed you yet, that's why it's your mission to make sure they do.