So, when analyzing cash flow I don’t accept the often negligible amount listed for repairs and maintenance.  

For example,  If the grill should start a fire would your insurance find you negligent?.

The purchase would likely need to be consummated at the higher price in order to establish the "damages" to which you are referring... and then I would refer you back to the other potential issues I raised with respect to a negligence claim.Responding to a demand letter with "go pound sand" is not the same thing as defending a lawsuit.I just don't see any attorney taking this $12K case to trial and that is what you are suggesting as the end game.

I also wonder if I'm overthinking it in that if something were to happen, wouldn't someone have to truly prove I was liable or negligent? 

For me, selling merchandise like coffee mugs, etc. out of the space sounds like a decent bit of effort for what would probably be a negligible return.I manage STR's in Hawaii, so we have a few options many folks don't have, but we are just beginning to try to sell add ons.

In my market a nice 3/1 might rent for $1350 as well but with an extra bathroom the difference is pretty negligible.

I can't see any type of gross negligence on my part that would wipe out more than that in a lawsuit. 

Tortious interference requires a negligence.  

What is my right as that was brand new and completely ruined due to tenants negligence?

I plan to give my tenants a proper notice to inspect the apartments for any damages negligence.