A subtrope of Fake Ultimate Hero.
In a world with The Masquerade, especially of the Urban Fantasy genre, people can be divided mainly as follows: Those that know what's going on, those that don't know what's going on, and those that think they know what's going on. Now, add some power and some involvement to the latter two kinds of people and you may get several results.
One of them is the Not-So-Phony Psychic. The Not-So-Phony Psychic is a person that thinks they know what's going on and/or thinks they know what to do about it. They don't. And they somehow have the power to make the mistakes that ensue. Sometimes the Not-So-Phony Psychic makes money off their "talents"—by screwing up, and badly, on national television, or at the very least by screwing up in private while thinking he's a great hero, or that he's cheating people (by screwing up for money).
Mind, the Not-So-Phony Psychic isn't usually a quack (though sometimes he thinks he is). He usually thinks he's doing it right, it's just that he doesn't know it better. Alternatively, the Not-So-Phony Psychic may well think he's cheating people off their money when he actually does dabble in the occult (and screws up). The "Holy crap, it was real?" look on their faces is usually priceless.
The usual formula for a Not-So-Phony Psychic intro episode is as follows: The heroes meet him due to his celebrity status or by coincidence. They find out he's doing it wrong on national T.V. or by accident when they see him "at work". They join him and fix his screw-ups, sometimes explaining how and why. And the Not-So-Phony Psychic is enlightened—usually meaning he'll still make money, but won't screw up anymore. The Not-So-Phony Psychic will sometimes remain in the show, sometimes aiding the heroes for what little it usually is worth. Sometimes it is worth way more, though, specifically when they use their fame or resources to help the heroes.
Compare Magicians Are Wizards.
- Don Kan'Onji, from Bleach. He has a show on TV where he "exorcises" ghosts, but he's actually making things worse. Ichigo sets him straight, and he pops up from time to time throughout the rest of the series.
- Later on, he pretty much totally sheds this trope when he punches Aizen in the face.
- Mr Satan / Hercule from Dragonball Z. He even helped save the world one time by use of his fame, getting people to help power a genkidama.
- The first arc of Ghost Hunt centers around a high-school girl who claims that she can see spirits and ghosts and the like... coinciding with some paranormal events in an old schoolhouse. Naru soon finds enough evidence to prove that she's just faking it in order to stand out and appear interesting - but then, with further investigation, realizes that she's a latent Psychic, and subconsciously CAUSING the paranormal events in order to prove her own stories. Later events uncover a Fridge Logic alternate explanation - Mai is later revealed to have a powerful psychic potential, and all the paranormal events coincided with her idly musing that it would be 'more fun' if there was actually something spooky going on. And the final test Naru used could point to Mai as easily as the other girl... if that's the case, then it doesn't actually fit the trope, but the show never address that possibility, so...
- Robert James Lees in From Hell. "I made it all up, and it all came true anyway. That's the funny part."
- Dirk Gently. In the Backstory, he pretended to be a psychic but everything he predicted came true.
- Sybill Trelawney, from Harry Potter, on a good day. She actually can See into the future, but only when in a trance that she cannot remember; most of the time she uses tarot cards and crystal balls, which are depicted as not working. (Though some fans have noted that they do foreshadow things uncannily often...)
- A minor but recurring character in The Dresden Files, Mortimer Lindquist, is something like this. According to his backstory, has magical powers called "ectomancy" making him capable of Dead Person Conversations at will and similar abilities, but due to misuse those powers atrophied to nearly nothing by his first appearance in the series. He makes his living as a medium, but it's mostly by conning his clients rather than genuine medium work. Harry, though, persuades him to take the job seriously again.
- Ghost Story shows that he's been practicing - Mortimer is still only able to use ectomancy, but in that area, he has just as much power as a middle-ranking member of the White Council.
- Marjorie Potts, AKA Madame Tracy, in Good Omens.
- In The Haunted Air, Phony Psychic Lyle Kenton has a run-in with a genuine ghost, and ends up developing real powers of foresight and acquiring a genuine spirit-guide in his brother Charlie.