Managing to successfully flirt with a stranger or new love interest is a true art. It requires enough attention and empathy to pick up on the other person's interest and comfort level, but most importantly it requires the other person reciprocate. The most amusing tales of failed flirting attempts come about when one party has NO idea they're getting wooed.
In the land of men dating women, it's still more common for men to make the first move, and given the way our dating culture functions - women are pretty much veterans at getting hit on and either sashaying away or returning the wink. Because of this imbalance, a lot of straight men are still pretty oblivious or confused about when women are actually making a move, which is equal parts amusing and frustrating - depending how you slice it.