There are hollow core doors throughout the property, and I don't believe there was a single one without a hole in it of some sort, plus damage to drywall, carpet stains, missing vent covers, the list goes on.  

., I would have served the tenant with a Cure or Quit notice - they painted the condo, which they weren't allowed to do and never asked, installed a kitchen backsplash that had to be pulled off the sheetrock, they stained the kitchen cabinets, they spray painted something on the patio and left a red paint outline, etc.

Was thar staining work or the type of wood, etc?  

There is a small concrete porch that I’m thinking of staining, or possibly painting to look like wooden planks.

We really like the look of white or off white furniture but are concerned about staining in an STR.

For sealing in stains like that (if is from smoking), use spray paint and then normal paint over top. 

There is a 6x10 water stain which flooring and subfloor will be cut out and replaced.

Knocked down a wall to one of of the bedrooms to create an open concept kitchen/family room (changed the original family room to a bedroom), insulated those walls, drywall/plaster, new electrical (all knob and tube), moved plumbing in the kitchen, new kitchen, painted every room and sanded/stained the hardwoods.Options for the unit the tenants are moving out of 1) Cosmetics (1 month - Rent out February 1 or sooner)- Paint rooms- Sand floors?

Your high-end cabinets are usually going to be painted white or black, or wood stained light or dark.

So we kept working & then we heard the woosh/splatter of the toilet flushing a 'number two' down onto the newly sanded but not yet stained oak living room floors & all over the beer cooler & tools.