I consider myself an excellent judge of character. Even short interactions with people usually can give me a good idea of their essential nature. It's probably attributable partially to instinct, alot of observation, and experience with a wide variety of people- from the scum of the earth to people with saint-like virtues.
Spotting sincerity or the lack thereof is a no-brainer for me & when people are being "fake" it is like a fire alarm in my head, though I never call people out who I don't know well.
Taking this quasi-scientific visual quiz solidified the confidence I have in my people-scrutinizing skills.
I would have scored perfect, but I went against my gut feeling on the first one... which was the only 1 out of the 20 that I missed.