I've kind of wanted one for awhile anyway, so this was a good excuse, and might be one tool to help fix this.I got in touch with the tenant and she's going to have the cleaner come back out and clean more thoroughly.

Furnish it, you furnish all utilities as well but cap the electric and water to a reasonable rate so they dont leave the door open with the air on and run up the billl, provide internet and put in a Ruko device, charge a cleaning fee (find a good cleaner), and you are ready to roll. 

Would you open a restaurant franchise or go after storage unit businesses, dry cleaners, etc?

I’ll be looking for a local co-host, cleaner and handyman.  

What HVAC installers have informed me is that keep A\C filter clean, use spray cleaner for coils when dirty, when most older A\C s were installed in Florida we didn't have the code requiring the retaping of vents with a quality tape to prevent leakage into the attic.Additionally the insulation, windows and doors are going to be contributing factors.You will be surprised how many people in South Florida do Not realize the amount of money being wasted by the Duct tape drying out and air venting into Non A\C spaces.

If I was doing a flip I would go smooth ceilings it just looks cleaner and sleek .

PreventionI will spray or wipe every surface that I touch using an approved disinfectant such as Lysol or Clorox.After each inspection, I will disinfect all of my tools using an approved cleaner.

As @Shaun Palmer mentioned, the buckets of water/cleaner turned brown quickly. 

I can change lock codes easily and remotely and give different codes to different people (i.e. the cleaner has her own code).

I used the steam cleaner twice a day to clean up after him.