With model railroad items, FUD is the way to go. However the fine detail does
present problems because the material is so brittle. Often this can be cured
by alterations to the drawing. I have had just one failure where handling at
Shapeways caused a broken detail, and it was replaced.
For quality control I agree, selling via a Shapeways Shop is out of the question, as
each print needs to be inspected. It would be nice if Shapeways kept notes on drawings
for best orientation in the build, especially for repeat prints. So far Shapeways have
been pretty good at it.
To date, I have not had any customer complaints, and any cleaning has been readily
accepted.