One of the worst cases of "mis storing" was a kit that I saw her in Vancouver about 10 years ago.
Two M3's. 21f3.4, 28 first generation, 35f2.0 version 1, Zunow 50f1.1 and one of the early 90f2.s in chrome. It had been left by the owner in his "hide away" in Belize. All the lenses had severe fungus, in some instances completely opaqued out (the Zunow). The curtains on M3's were green with mold and disintegrating. The finders had severe mold and fungi growing in them. I handled them gingerly (and wished for surgical gloves) and informed the owner "It is a totally destroyed kit" - He was a bit upset, but he managed to find someone who gave him $1000 for it all. I did not want it - and my instinct was right. The new owner spent about $3000 restoring the bodies (virtually replacing the complete chassi) and the 21/3.4 and the 35f2. Both the Zunow and the 90f2.0 were beyond salvage and the 28 flared at the mere thought of a lightsource.
The owner had bought the kit new in the mid to late 50's and shuttled between Belize and Canada. He left the kit down south as he was switching to 120 - and the Rolleiflex F in the case (with the 75f3.5 Planar no less) was rusted solid and had a small bug living in the mirror housing!