I am completely unqualified to answer, but after I've sorted out what tube types I have, I'm sure fellow head-casers will be able to make suggestions.
Rocky & Bullwinkle jokes aside, they do what most rodents do: make a nest out of whatever is handy (tearing up the insulation), poop everywhere and pee all over their nest. The end result is especially disgusting. Imagine a 1/4" thick layer of squirrel shit that is fused to the floorboards of the attic by their own urine. I spent an hour in one area, wearing a dustmask and goggles, scraping it up in chunks and then vacuuming up the debris. I still have two more locations to clean, I am not looking forward to them.
Yes, this makes perfect sense to me. However, I can only report the condition in terms of appearance. I don't have a tube tester, and the tube equipment I do own (vintage radios and some ca. 1970 McIntosh gear) is not suited to the task.
I am sure a lot of the tubes I have are of little or no interest to audio snobs if I have one or two "hits" (as they call it in the antique business) with desirable tubes, I'll consider myself lucky.