Certainly there can not be a girl that hasn’t heard this line or a guy who hasn’t uttered it. Unfortunately, it’s complete bullshit. It’s a line designed to flatter your ego and ease their way into your panties. It is a very effective means to an end.
The line works because it makes you feel special; as though you are the only person in the world with this magical connection to this other person. It attempts to establish an immediate familiarity, a fast forward button to intimacy. It turns that guy you barely know into “the one.” I’m not saying that people don’t connect in unique ways, they most certainly do and you will connect with lots of people over your lifetime.
When a guy is throwing down a line like this too quickly, you would be correct to feel suspicious, not closer to him. Consider his intentions for saying it. He may want sex (okay, they *all* want sex) but he might also be a love junkie (addicted to the high that comes with the flirt and not in it for the long-term, even if he’s unaware of his status himself).
So don’t confuse that rush of hormones with knowledge of or experience with the other person. Make sure you know them, not just their lines.