Sometimes we get smoking deals on properties because they have a material defect that the seller doesn't know how to fix or can't afford (foundation issues, black mold, hoarding, etc.).

They get stinky mildew between the tracks, they get stinky black mildew outside the tracks and frames, they leak and damage the floors, the glass is hard to keep clean and I personally had a friend who slipped in a shower, fell through a glass door, cot cut bad, passed out and bled to death. 

The worst case would include mold remediation, sagging flooring, woodrot, drywall damage, depending on water type - clean, grey, black water - foundation damage and/or repair. 

My job is to fly a helicopter and search for schools of tuna!

after seeing this black swan event of Covid and rent moratoriums that were out of the investors control..

There is a jut out wall where the fireplace is, and I am considering painting it black or dark grey (and the rest of the walls white).

The mold is showing through the ceiling, known as ghosting, black mold has grown all over the ceiling edges and down the walls. 

It will have black market value ......and that may be where this is headed.... 

Ive looked at banks, including Black Oak and some others suggested on bigger pockets podcasts.

If there was a black and white playbook with simple answers to every question, everyone would be rich from real estate.