For instance, I am replacing a heater filter today in one of mine - when I do this I will also conduct a visual inspection of all plumbing and electrical as a courtesy to my tenant.

I appreciate you adding links for me to visualize these things.

Most of the bids were not very specific in the type of finish materials they would use (I assume finish materials mean the "cosmetic" stuff the ADU renter would see visually such as tiles and flooring). 

No one is an inexhaustible tower of power that can just shrug off one failure after another with some positive visualization and good vibes.

They have the visual in their mind of a place that needs work, and that is the image they tend to keep - that they are living in a unit that needs work, so they will find work for you to do, in my experience.  

Pictures added for visuals.

Thank you for making me visualize the gory possible outcomes of renting to someone like this. 

They can probably do a visual inspection immediately and indicate whether it is likely or unlikely, then they can conduct a physical test of mold in the air and on surfaces.

Adding a camera allows for visual of activity as well.

Jumped onto my trusty 3d software for a quick visual.