One of my favorite restaurants has a black spray painted drop ceiling.  

I had the tub in my home professionally done 10 years ago it was sprayed ,cost $ 300 .

I know this not acceptable so I am thinking I need to remove the debris, spray for mold, paint with mold resultant paint on the joint beams to be safe, lay insulation plastic over the dirt.

Easy solution: after writing the information on the tag, spray it with a bit of flat or satin polyurethane.  

I looked into spray foam.

Look that up and how to insulate a rim joist with polyisocyanurate foam and spray foam.

I’m looking at those that are just rusted and still work.Has anyone just spray painted with an appliance spray after sanding or chipping away any loose pieces?

I even have my equipment to spray bathtubs, cabinets, tile, countertops and the chemical supplier in my contact list. 

@Jack NiI would spray vinegar in the tenants eyes for letting them destroy the property before I’d fool around with getting Fido to stop eating it !

I did install all new baseboard myself which I sprayed before hand so that cut down on the price.