Thats a bit of a silly poll really...unscientific at least unless you take people who live in the same place and do the same mileage!
I have white wheels, I live in Scotland, its the middle of winter, the roads are black and slimy with grit and salt, I do 2000 miles a month and if I drive to the end of the road the entire CAR needs washing - nothing to do with the fact that the car has white wheels...