J.J. seems to be a very outgoing person. He tries to act as if he knows a lot about the business so artists will sign him. He is very greedy because he wants to be rich and have lots of money.
In One Day Wonders, J.J. sees Jessie and Luke performing in Central Park. As we learn later in the episode, this was his shot to find his next victim. J.J. tells Jessie and Luke he wants them to record a video. Excited, Jessie and Luke accept. Soon, they find out that J.J. is a scam artist. He told Tony he could produce him to be a successful kazoo player. But once he got the money, he ran. So Jessie and Luke confront J.J. and leave him.
It is unknown how many artists J.J. has done this to.
He doesn't actually make you famous, he films a video that you can easily make on your phone without paying 1,200 dollars.