How do you know when a psychic service is a scam?

I agree with the others, all psychic service's are scams. They all tell you general stuff that could be relevant for everyone; just like in the horoscopes in the papers. Once in awhile they may come up with something specific but it's just a 'fluke'. I'd tell your friend to 'run' and don't look back. There are way to many people that live their lives around what these people say and that's not good at all.

they're all pretty much scams. If you just sit there and say nothing, then they will never go into any real detail. Trust just stay away from them. Unless they show you some amazing proof like they can name every member of your family.

Bingo! It is a scam, psychic's are false. I am tempted to become a psychic because it seems so easy to con people out of there hard earned money. It should be a crime.

Well, for me, all psychic services are scams since psychic powers are an unproven fantasy that has been tested many times and failed. The hiring practices of these firms are pretty well known from the many court cases against them. They hire people off the street and give them a crash course in "cold reading", a magician's technique in learning information about a subject and making it appear to be paranormal. Amazing how many of these services cannot foresee their own demise in business (Psychic Friends, Miss Cleo, etc).