In a night club or a place where a guy is clearly running a routine, here's a good trick to see if it's really working. Have some cigarettes, walk up to any one of the girls in the group and say as normally as if you would anything "Hey, you got a light?". If the girl isn't into it. She will respond quite positively. Then you can follow up with "you having a good time?" Kind of laughingly pointing at the guy while you're saying it. At that point you can immediately infer that she's already called the guy on the act and is looking for somebody more comfortable with themselves. At that point all you have to do is sit back and make fun of the clown while you pull his females.