Thankfully I have never had that problem before. Sounds godawful.

I did have a problem with a parts car years ago that I kept in an unheated and un-monitored garage (wouldn't enter it for months) with mold.

I remember needing a seat belt for my than daily driver (old '80's Citroen hatch back) and thought I could easily get one from my identical parts car. When I opened the door to that car for the first time in months, I realized the steering wheel and the seat belts were covered in fuzzy white stuff. Pretty disgusting. Smelled like wet dog too, I think that garage had a problem with moisture.

I never intended for that parts car to ever go back on the road though, so I didn't care much. Still something to keep an eye on I guess.:)

For future reference, "Nature's Miracle" cleaner is actually a miracle-it is actually strong enough to get tomcat stink out of carpet/fabric/etc. Foam you're SOL :D

came across the best 5 gal bucket mouse trap video I've seen to date
https://youtu.be/l4PaGvAhV9I

This, from the manufacturer, may be of interest...
 

Mercedes-Benz Specifications for Operating Fluids: Overview Sheets

Select: 381.0 Preservation instructions passenger cars