So is anyone admitting that they he absolutely sucks at this?
It's similar to 'how big is your penis'. Those who are proud of their abilities will state them. Those who are not will choose not to answer the question.
My take: I'm good enough in psychology to realize people who care about it will tend to think they're good at it, by remembering all the times they've been right and (unconsciously - it's the darn brain !) omitting most of the times they've been wrong.
And no, I'm not very good in psychology.
I do remember trying this kind of "deep mechanical understanding" of people when I was younger. I guess I outgrew it.
People can know my personality well and still have trouble "predicting" my actions/reactions well... good enough for me. Being completely transparent would suck.