Gotta confess, pure white's a beeotch to keep the grease smudges off of. I first painted my Notch rattle-can white when I first got it (stoooooopid) and EVERY little smudge of grease around the hood and fenders stuck and showed horribly. Bird poo left ghost stains. Road tar was a constant annoyance.
Now, with black, my biggest problems are (again) bird poo, water spots that never completely go away, dust, and the old white paint showing through where it flakes off from the front (I need to strip/repaint the nose).