Thanks, I came up with it on my own, long away and in a far away place.
I believe that the reason it works is because it throws the girl off balance when you walk away. You throw out the smile line and more often than not she’ll smile (even if it’s involuntarily so). Then she’s deciding whether to talk to you or shut you down, and before she’s made her decision you’re walking away. Then when you come back 10 or 15 minutes later, she’s intrigued enough to give you a chance.