For a C class rental I would probably paint the walls / ceiling if they show wear; fix any dilapidated issues with cabinets / plumbing / floors / fixtures / doors / windows.  

Last time I was there, there was spegitti sauce on ceiling, the walls were covered in crayons. 

Based on my old friends in Michigan, they are not effective enough alone compare to the old forced air furnace especially if you have a high ceiling and larger space.

The unit below ours is experiencing leaking from the ceiling.

There are other concerns as well which could arise as "Big ticket items" like the Electrical service/panel, ceiling height concerns, natural light and ventilation requirements, etc. so a more detailed review would definitely be necessary to provide more clarity as to what the best options may be to move forward.

Used more than 25 boxes of mud to cover the ceiling and walls to remove the textures.The house had a good floorplan, 2 beds on opposite sites of the home, a bath in between, and a large open space/dining room between the kitchen and the living room. 

Poor layout - these older homes usually have sloped ceilings, low ceilings, weird layouts that don't flow.

Turns out this lady is a hoarder...things literally stacked to the ceiling, piles of junk everywhere, bags of open garbage, rat droppings, etc...It was truly disgusting.

ISLAND on wheels with same Butcherblock countertop chalkboard wall of dining area. bathroom, black marble showerstep black-rock shower floor, white subway tile floor to ceiling paned glass shower.

I didn't move forward with that home due to the ceiling being low, but I was looking at the lack of egress windows as a potential value add opportunity.