Haha, I HATE that! You'll see some really hot chick working out (trying to) and when you decide to say something because she's giving you that "I'm miserable, help!" look, in comes Captain Awesome to pat her on the butt and say, "great job honey!" Of course he shoots a glance around the room to not only make sure EVERYONE knows she's his, but to "scare" off the competition.
Some are really subtle with it, I don't know - I was pretty quiet as a young teen and missed a lot of opportunities because I didn't hone in on it. By the time I figured it all out, I was banging 5 chicks at the same time and met my wife. Ended that adventure before it truly had time to blossom into a story for the grandkids.
I'm telling you that you need to join that planet fitness. If I were single, I'd so do that just to be the alpha male and pick up on the hotties that are looking for such.

Then again, they will have their guard up, so it's something that's probably going to take some time to put into action, but totally doable.
I want to do the same sometimes, but how do you take a pic without being creepy? Pretend to be texting and turn off flash? LOL