Ha! This reminds me of several boxes of loose G1 Transformers and parts I bought many years ago. They were from a collection that someone scrapped together by going to garage sales and flea markets, so she was a junque aggregator!
My brother and I wore gloves and dug through there cleaning off each part one by one. Quite a lot of fun since the smaller guns and accessories were hard to identify and some turned out to be pretty valuable once you could properly identify it. But to get there, we had to work around dead bugs, rug fibers, hairs of all types, and general grime. The worst were the various dried liquid stains that we told ourselves was perhaps grape juice or Coca Cola but definitely not blood, oh for sure not blood. I was worried for a while there, but neither of us contracted ebola or the plague. Good times.