Crapola consultants can't create clean copy
Meta-data? Jeez, Loueez. Everyone knows that you remove all those extraneous markings from your Microsoft documents. As far as I know, that's one of the major reasons we convert to PDF (no fan of that either) - to get rid of those hidden tags in the Word/etc. document.
Of course, now it's much easier. We used to spot plagiarism by looking for sections of exact word matching. Those loverly AI folks at google/amazon/etc have enhanced these to locate large texts/etc. that sport a reasonably high rate of "similarity". Shit like moving sections of text or substituting Jack for Jill don't work any more.
One of my favorite tricks in school (as long as I lasted) was to take a potential block of text from a foreign language oeuvre and translate it in my own words. I got several positive grades from that technique altho someone called out my "stilted English". Nowadays, I suspect that google/translate would also detect my boyhood misdeeds.