I'm not from McAfee, but I can possibly validate your experience.
I have a rule that triggers an alert on Corrupted Media Type, but doesn't block the traffic. To date, most of the alerts that I've seen are for PDF files. For example, in my environment, out of 1013 Body Corrupted identifications, 943 are related to PDF files.
Out of the 70 that weren't triggered by PDF files, 32 were triggered by facebook.com URLs and the rest were various other domains.
Did see a post from 2011 that stated that the PDF opener didn't like some specific feature/option and would trigger a Body Corrupted condition.