That's probably because those nasty cabins are covered with all kinds of live tissue. Probably a bisexual bacteria gangbang going on at a level invisible to the naked eye.
They should test for plague and polio or live Dinosaur DNA just for fun.
Wife wanted to rent an RV a couple of years back. I told her she didn't want to. She said "YES I DO, YOU'RE JUST CHEAP"
I said no you don't and I'll prove it. Took her to the rental place on the corner of sunset and gibson and walked her to the open display model.
Told her to look in the nooks and crannies. There was scuzzy slime everywhere. I asked her what she thought the rest of them were like if the display was filthy. She wanted out of there ASAP.
I am cheap but knowing she is a neat freak was the Ace up my sleeve.