Obviously every market is different, but in my opinion spray foam insulation for roofs is going to be the best ROI for reducing your expenses (especially in Texas). 

We called for the property management company to come spray the property over summer since it was infested with bugs really bad.

Is it still a complete and functional home if there's spray paint on the walls, a hole in the drywall upstairs, only one functional bathroom, and a cracked window in one of the bedrooms?

The smell of cat urine, and more-so, spray is near impossible to remove once it is embedded in the subfloor ... it's even more tenacious than dog urine.We bought a property where tenants and their farm had been for 9-years ... it was a complete gut job - even the concrete slab, under the subfloor had to be treated to remove the smell.Good thing your tenant is paying over market rent as they longer the felines stay, the more it's going to cost to be rent-ready for the next tenant.

I wonder if you can spray-prime the mirrors on the ceiling and paint.

Frequent inspections, perimeter spray all units, and treat each occurrence asap.

In polished chrome, with a pull-out spray that keeps things streamlined.

You can also buy a Termidor spray foam product that will piece through sheet rock and you can treat inner walls as well.  

Spray cans do a decent job too usually but have to mask off the area.  

Papa's unfixed, spraying Tom  cat doesn't end up 'being watched for the weekend' anymore.