I haven't read the whole thread, but I worked in pre-print for a printing company. I think it's gone bust now as it goes.
Inside it was very chaotic, and a lot of the staff pretty much moaned constantly about the customers. The best thing you can do to prevent that is obviously do your research and try to get the basics right.
The problem I often saw, was that the client would want something that would look stupid; the printer would tell them it's going to look stupid. Then they would have a sample and either say it looks stupid or go ahead and run the print and then decide it looks stupid.
The honest feedback is a good thing generally.