Jeff;
I don't think you are full of it at all, and indeed, your theory would
partially explain why two X29's painted at the same time could look
completely different 5 years later.

If X29 #1 took a load of machine parts out to LA, and then spent the
next 5 years being shunted around various parts of the arid southwest
carrying non-mineral loads, before going home, it'd look a lot different
from X29 #2 that just shuttled back and forth between Youngstown and
Pittsburgh and Cleveland and Weirton hauling a variety of nasty loads,
including lime, steel-making additives, barrels of solvent, etc.

There is a series of photos of X29 rebuilds in the "Color Guide" series
that just fascinates me. All were built in the same time period, and
repainted on various dates. All exhibit TOTALLY different weathering
and evidence of past loads. One was clearly used in flour or other fine
powder hauling, was not repainted, and looks terrible. Others have been
repainted, but exhibit varied weathering including rusty patches, or
just streaks, or minimal weathering, or totally scoured of paint, etc.
And the roofs range from totally peeled paint off of galvanized steel
with little patches, almost untouched paint, rusty patches, and
Asphaltum! Crazy! It is a modeling project on my "to do" list, in a
big way!

Here's another one: I always noticed that the few far-away hoppers I saw
in local consists (an occasional Santa Fe, Burlington, or SP) always
looked in much better condition than those born locally. I suspect it
may have had to do with where they spent most of their time, and not
because somebody used better paint. With all the rain falling on acidic
coal loads, in the northeast, could it have been that these hoppers were
literally being eaten away?

Take care,

Elden