Yes, that could be an option too, though in this case it would be surprising given that this was a new subcontractor of our actual client, in a place neither of us have ever been before. But I recognize the phenomena you mention; I sometimes see random people on Facebook with surprising amount of overlap with my social graph, even crossing the groups I consider mostly unrelated (say, a person is a friend with few of my buddies from university AND some other unrelated group of locals AND also knows that random person I met somewhere that lives on the other side of the country).

That does seem hard to explain. It's creepy sometimes to wonder just how much they can figure out from how little and where all the information siphons are actually located.

Honestly, I find it both empowering (oh the data I can find if I know where to look) and reassuring. Why reassuring? Because it reminds us that lies can and will be discovered. Some people like to think they'll get away with one but it's only a function of how much someone else cares. But reality is self-consistent and in the Great Web of Causality falsehood is just damage that needs to be routed over.

Conversely, lying is a malicious act. It'sdirectly sabotaging the model of the world and reasoning capabilities of other human beings, with recursive damage being dealt as that person propagates or reasons from false information. Unless placed in life or death situation (std::jews_hiding_in_your_basement), you really shouldn't do it. It boggles my mind how lightly people treat spreading falsehoods.

I think things will eventually come around once reputation in life is unavoidably attached to everything they say, though, but it might be messy getting there.