The idea is that they aren't supposed to realize by some deep sense of foreboding that anything out of the ordinary is happening at all. They are supposed to think that your thoughts are actually their own. And to expand upon what Trick said, keep in mind how few people have the level of self awareness to distinguish between their own voice and another person's. In a way, most people are a slave to their own thoughts and emotions and demonstrate little to no control over them.
First of all I have had tremendous success using self hypnosis. Don't give that guy any money. All you need is to learn how to write a script, then write one and record it with a digital recorder you can buy at Wal Mart for $20, or even an old tape recorder you might have sitting around the house. Secondly hypnosis is not necessary for "unlocking" anything. I can't blame you for wanting to though, some telepathy articles aren't all that great. What you really need is proper training which makes the "advanced" techniques the same as the beginner techniques very quickly.
My wife doesn't use the definitions that come with any deck but she is eerily accurate with what she gets from them. I think that the cards themselves don't tell you much.. but at least for my wife they seem to help HER interpret her own feelings. I think it's more individual than simply "reading" the cards.