A pice of PIM can be meaningful or aesthetic. The true criteria for PIM, and believe me I've seen lots of it, is based on the artist. It's the artist's intent and purpose in creating the art that defines PIM. If the message the artist wants to convey is "I am soooo smart/talented/avant-garde" then the piece can be considered PIM.
It's important to remember that, as TheLady said, a piece of PIM can be valuable, meaningful, and beautiful to any other observer. It's just unlikely that it will ever have any true value to the artist. An important part of the benefeit an artist receives in creating art is the process; a pseudo-intellectual corrupts this process with his/her desire to impress people.
The meaning of art comes partly from the artist and partly from the observer, in this case it's mostly from the observer...