Your post made me think of another question for you. If psi results are largely unpredictable, then how can that be classified as positive psi effects when it could just as easily be considered "by chance."
What you are essentially saying in your post is that no one has displayed psi capabilities on a predictable basis. If that's the case, then no one who advertises themself as "psychic ..." is legitimate. To put your words to it, that's a pretty bold statement. How do you know this? (Actually, you don't have to answer that. Just trying to show how frustrating those kinds of comebacks are.)