This must be why my wife asks me if I'm 10.
I go by the size of the hands, fat men with fingers that look like Vienna Sausages are a tip off.
Men that have long fingers and small wrists are a tip off.
Men with a lot of hair on the top of their hands is a tip off.
Men with lots of hair on their palms is another sign of something interesting.
Then check out the nails, do they bite them to the quick or are the well maintained or manicured.?