I always wear gloves and put newspaper on the work surface before taking keyboards apart now.
I've taken to opening a garbage bag, and setting the shipping boxes in it before opening them. Started doing that after getting a luggable vintage PC that was full of rodent feces, and a TTY device that had a couple dozen roaches in it. Considering I'm violently allergic to cat and dog hair, I should probably get a pack of those disposable dust masks.
The things we do for our hobby...
So do I now; goggles, respirator, rubber splash apron, and thick rubber lab gloves, sometimes leather work gloves for bulky items.
The local couriers think I am a nut job, and I get a lot of packages...
I bought a case of CFL panels last year, the shipper decided to ship them loose in the box without any packing material other than a few handfuls of packing peanuts. Beside the vast quantities of broken glass I had to pay for hazardous waste cleanup for my workshop and notify the shipping company that their employee may have come into contact with mercury and phosphates. I still haven't gotten a refund from the seller for the items themselves, what a jerk

....
But yes I had gloves and a mask on when I found the condom. Called up the seller and apparently it was a joke played by one of his employees; supposedly there was hand sanitizer in the condom, not biohazardous material.
When I did PC repairs frequently I saw some horrific things inside of old computers and TTY consoles too.
Found a live rat in one once.
It has always made me wonder how people can be so nasty.
Back on topic, I normally take model M's apart and give them a good deep cleaning when they come in. If you are planning to bolt mod anyway you might as well strip it down and soak the barrel plate in hot soapy water at the same time that you do your keys. I have found that long plastic tote boxes do a good job of holding everything with enough room to completely submerge everything.
Labels get cling wrap and tape over them for protection.