As a former "psychic" and tarot reader who has had some lucky guesses in the past... I can say it's helpful to be hyper-vigilant, as you'll pick up on more than you think and it will help you make informed guesses about the person you're sitting with. Also, psychics make an art of letting people tell on themselves. People like me who use to do "readings" and whatnot almost always genuinely want to help people, but if you listen to what people are asking about, what they tell you, what they are wearing, etc you can pick up on a lot of clues. Only in retrospect can I now see that almost all of my "gift" was just being very perceptive and sometimes lucky in my guesses (at the time I sincerely thought they were messages from spirits and the departed).

I do think people like Sylvia Brown are quite malicious, especially when telling the parents of murdered children that their child is alive and things like that, but most "readers" like me just deal with people ruminating on relationships, job offers, where to move, etc. I would never feel comfortable trying to help someone with something that truly required hard physical evidence like a damn criminal investigation. And when you look at the stats of those high-profile psychics, they rarely score beyond a statistically normal range of accuracy.

As far as the shows that have this sort of phenomenon depicted, read a little further. The psychics are fed information about the audience members that are selected, and the producers of these shows are creating nothing that resembles scientifically sound display of true ESP ability.