Logical inconsistancies

I was out with a friend at a fantastic coffee place, when another of her friends comes by and they start to talk. At this time, there's a guy who's sitting at the other end of the patio keeps glancing over at our table seemingly checking my friend's buddy out. Not surprisingly, the conversation quickly shifts to creeps who never fail to "check girls out" and how guys should keep their eyes to themselves. The conversation then shifts to a guy that this girl has a crush on and she complains without a hint of irony about how he never looks in her direction... at this point, i'm sorely tempted to ask whether a guy needs to be psychic to figure out when a girl wants the glances or not... but i hold my tongue.... not wanting to be attacked by my freakishly strong friend....

I will leave it to y'all to explain to me how to develop these telepathic skills/ radar that will enable guys to know when to look and not to look.... is it really just a unique case or one that is more common than that?

of course, this story has a great ending... the "sketchy glancer" picks up his white cane and leaves with his other friend guiding him through the tables to the exit......