I wonder if this is because these sociopaths and professional liars are not really lying.

It’s kind of like one flew over the cuckoo’s nest- if everyone is insane, and you are the only sane one, actually everyone is sane and you are the only insane one.

Maybe they are so good at lying that it isn't a lie anymore, they really belive it. It’s truth to them, so there are no microexpressions not because they’re hiding them but because they really aren't experiencing them.