here's the thing: white things get dirty. I had a white MB, and then I started looking around my labs (I'm a graphics major - lots of macs walking around) at some of the older iBooks, and it was awful. That, along with how easily the outer casing picks up scratches, and I knew I had to get a different computer.
Now, don't get me wrong.. I know there are people out there that clean their white MBs/iBooks every week and have since it was new, and those are probably still pretty good looking (minus the scratches).. but I don't want a computer that needs that much maintenance.
I moved on to a black MB, and the smudges were just.. horrible. Granted, I would rather have those because they're easy enough to clean off, but again with the maintenance.. I'd clean it, and within an hour it would have fingerprints and smudges all over it again.
Truly, the alum. casing is the best.. hardly shows dirt or smudges.. you can actually *gasp* touch your laptop!