Psychics are lucrative. They prey on people in the most desperate times of their life and often make off with their life savings. That's why there's one right next to the Louboutin store in Beverly Hills.
"Credit card only" is a sure sign of money laundering: it's a way to game the cash vs credit ratio.
(Edit: maybe "sure sign" is a little bit hasty, but I think the other possible reasons for a "credit card only" sign are actually worse morally than money laundering)