For what it's worth....white seat belts will get really dirty and will show the dirt quickly. Factory white interiors had black seat belts.... for that reason.

Hand oils will soil any seat belt....if you have ever taken a wet cloth and washed a normal belt, you have seen how much crud gets on the webbing. Your steering wheel is worse! I wash the belts and interior parts of the truck every couple of months and am amazed at the crud that comes off.