A rather foolish, gambler's-type question.
Asking the right questions, and approaching the market the right way, and having the correct, calm mindset are not only ideal but vital to trading.
Reading people, is similarly to trading, you are constantly sizing up the person or market or chart and scenario.
Analyzing their potential strengths and weaknesses, to accomplish their goal or fall somewhere between the cracks.
Kind of like poker, I suppose, but with more stuff to consider...rather then simply playing a mind fuck, assumption game by staring at them.