Has the quality of press ready PDFs improved in the last two years?

PDF is now over 20 years old. At some point in time, one would expect that everybody knows what is feasible with the file format, how to create a proper PDF file and what the pitfalls are. Many prepress guys keep telling me that this is not the case and that they still receive the same crap like ten years ago. I find that hard to believe so it was time for another poll, which ran from January to March 2015. Here are the results:

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