Since I starting scale building I find myself starring at the oddest things in the world. When I'm driving I find I'm checking out the exact way that the rubber part of the mud flaps on the truck in front of me are attached and the exact pattern of the rust on the tailpipe...

As I've said other places and will now say again, I'm certain that the key to scale modeling is "depth of vision" -- you simply can't model what you haven't noticed.