"Not for Sale," the 46-person mishmash at P.S. 1, is a thankfully rare case of "When Bad Ideas Create Passable Shows." Before we look at this slipshod exhibition, let's consider the flawed notion that created it. Alanna Heiss, the trailblazing but here totally misguided curator, writes that "Not for Sale" contains only art that can't be bought. Thus, the exhibition -- which will be open for another week -- is composed of work that artists either kept or, in a couple of weird cases, sold then bought back. By this curatorial criterion, nearly every artist on earth could be included. Heiss compounds the problem by haughtily stating that the show evinces her "unfortunate allergy" to the marketplace.