Just recently did a print job for a regular customer. Not a small time outfit, either. Like, they employ more people in their graphics department than the last four companies I have worked for combined. And they give us what's supposed to be print ready artwork.
Our finishing guy says, "hey- this has some spots in it. Do we need to reprint?" I took a look and said "well- considering they called themselves the city's 'favotire' provider, yes."
It happens. I'm just always a glad when it's not my fault!