It looks to be in pretty good condition, but the plastic safety tab on the washer was broken, and one foot was bent from dragging around.

For instance, the bathroom has a plastic tub, obviously, if they used scouring powder to clean it there would be scratches, so I wrote down products that are acceptable and not acceptable for different areas of the house. 

What is wrong with taking out the fan/light combo completely and covering the hole with a plastic cover?  

I would put a lot of plastic down on the ground, drill a small hole in the sag to let the water escape. then once done cut a hole in the ceiling and have a plumber try and determine where the leak is coming from.

What I love about the Marathon water heater is the tank is plastic and the tank has a lifetime warranty.

Bad management.Honestly it's bad for the tenant too, they begin to believe they can have a nicer house than they can really afford, and it's going to be a bigger shock when they have to leave and realize what a deal they were getting.If you really want to keep your property nice and your to do list small, evict everybody and cover everything in plastic.

Is that orange piece a plastic pipe of some sort?

I'm doing a remodel for my sister who lives in a fancy updated 1980's 3/2 modular and taking out the old kitchen cabinets a crew put the drywall right OVER the existing old original thin wood plastic walls that go in those things.

I am always finding plastic coins in our laundry coin boxes and they work very well for the tenants.

You'll find plastic "caulk savers" that work on the same principle, but they don't work better than nail/screw and tape.This treatment won't work with silicones sealant caulks, because once it's exposed to oxygen, the clock starts ticking.