During the next rain, the roof leaked again (water was dripping through seam of the ceiling and pooling underneath the paint, causing it to bubble).

Many tenants will just let you fix the leaks after they move out or maybe once the ceiling falls in.

Any critters or other movement could expose the wiring within the walls/ceilings with palpable risk of fire.  

They really are simple units.I would take care of vitals before you hit the popcorn ceiling and granite as well.

In those situations, you can buy thermostats where you have a master code and you can set a floor temperature and a ceiling or min and max temperature for tenants.

All kinds of issues...electrical outlets ungrounded, plumbing issues, flooring issues, a deck that was built wrong, a new master bath that didn't make any sense with a shower door hung wrong, a shower pan that had been nailed through, roof repairs made with 3/8" plywood, roof leak "fixed" by caulking the shingles.....new vent boot that wasn't nailed or seal, bath fan this venting into the ceiling....an unreal list.  

Ceiling flat white and walls Sherwin-Williams 6078 Realist Beige in satin.

To give a general idea of some of the mess they left - left it with 2/3rd of the lightbulbs burnt out, holes in 4 doors, very poorly patched holes in the walls in more than 5 locations, missing showerhead, missing ceiling lights, excessive mold, large hole knocked into paneling, enough garbage to overflow a roofing trash trailer, 2 tvs (1 stood 4' tall), cobwebs and filthy walls, excessively filthy carpet including over 15 dog male (squiggly!)

I ended up countering by giving a financing ceiling for the total $$ I could spend rather then dictating the terms I wanted.

Corrosive to HVAC plumbing and electrical very hard on the Lungs especially for a compromise immunity system, to identify the Chinese drywall go up in the attic and look at the backside of the drywall in the ceiling you will see Chinese printing in red.