I have one, he's black, 6 yrs old now.
Since he was a kitten, he never could figure out how to bury his own crap. Instead of scratching at the dirt, he'll scratch at everything around him (walls, litter box liner, anything but the litter) for about 2 minutes, making a hell of a racket. End result? Annoyed owner, and putrid scent of exposed cat feces.