Well, the Pistons have one on an expiring contract. The Pistons also have a need for perimeter defense and three-point shooting.
I don't need to sell Pistons fans on getting rid of Charlie Villanueva (especially with Jonas Jerebko and Tony Mitchell on the roster). And while he's not an elite shooter, Ariza's pretty good when he doesn't have to do too much other stuff. He shot 36% last year.
It's low risk for the Pistons (and the Wizards if they're not too attached to Ariza). The Pistons might have to throw in some cash because CV makes about $800,000 more, but this seems do-able.