I get a lot of 3rd party "print ready" pdf files that really aren't. We never print the pdf's directly, we always import to Corel and check sizes and set up for multiple prints as needed. Trouble is not many "degreed" designers know how to set up a pdf to be cross compatible. i.e. convert fonts, rasterize transparencies and such. They also ignore instructions to NOT send with prepress marks or bleeds. Don't need to go into detail about those troubles here though.
Seems they get insulted if I explain that I am forced to rasterize their pdf in order to make it work. Fonts are missing, transparencies coming over as flattened etc. They're completely dumbfounded and perplexed by my explanation.
Listen, if my vendors don't make money and I don't make money let's go fishing and drinking beer!
Tell me what you want and need, and I DO IT! You make money on my project therefore you want to prioritize my work if I need it and ask for it. DUH! We work together or sink together.
In reality I found that I had to bill for the fixes and get rid of the clients that complained. When I did that, my profits went up!!