As for UPS, I don't think I have ever seen a dirty UPS truck! it is part of their image to look clean. Their planes, and trucks, are their image.
As for dirty planes, I too have flown on some of them and seen others. I agree with others on this thread that its competition, deregulation. Planes dont make money on the ground. Also, cleaning people are another expense that can be cut.
I have noticed that airlines that have new paint schemes tend to clean and maintain the NEWLY painted planes more than the older ones. This may be due to the fact that the newer paint colors represents the company's image better than an old jet or the old colors. For example, most of Delta's new painted jets look good - even the 727s. But the ones with old paint are allowed to remain- including one 757 that I saw last year that looked like it had a sandblasted nose. With Southwest, the NGs are the ones that they want you to remember, not the 737-200s, so a lot of those are dirty.
That's just my theory. Anybody else agree?
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens