Just refurb'ed a DC26, and it was full of mud, an insane amount of polyester stuffing (the type inside stuffed animals/pet toys) and the turbine head clogged with damp Wal-mart receipts pressed into a solid mass. I'm new here (Hi!) and might do a little writeup on the process.
Way way back when, in junior high, I worked on a project that required a high-wattage fan motor, and someone's parents' friend donated to us an old Hoover that had been run without a bag in place. It was inexplicably filled with the obliterated remains of a head of garlic...
Mildly related, but I'm always astounded at how many eBay listings I see that are proud to include a half-full bag already fitted, as if old carpet dust was a great bonus.