Yes, this is generally how it is done. Even the "on-air" stuff like Miss Cleo, you can tell the questions asked are not too specific, something that may be partially true for most people. People get tricked because they "want to believe".
That being said, I used to have a good friend who is fairly intelligent who believes in it, and does tarot card readings for friends and family. She claims to be fairly accurate. But then again, I don't think she could tell specifics. I would always hack on her and say things like, "Hey, what did I eat for breakfast last Thursday?".