As PQZ displayed, they are believable because they say things that will definitely come true, like, "You will get hurt at some point in your life." Or, "You will have the oppurtunity to eat a hamburger somewhere." And then if they want to add something mystical, they will say, "I see in the distant...or not so distant future, you running like wind across a lawn, or a track, or a field, or a roof. The rest is clouded. Do not attempt to ask me real questions about people with names or specific events relating only to you. It is of the forbidden arts." thats about all there is to it. In fact, I might just take up psychiatricness (real word?) myself.