He put in a hot water heater, painted the upstairs walls white, put black shutters on the house, painted the deck grey, and painted the front door red.

But even if the numbers looked good going in and a black swan event happened, it would take a lot to lower the value of the house below your purchase price if you are doing value-add renovations.

But not the reason to do it.Good insight here from @Michael Plaks (the Black Belt) 

I know what agents in my market have a reputation for lying or stretching the truth.The other way is you can ask for a copy of the other contract, with names blacked out.  

Purchase price: $650,000 Cash invested: $65,000 STR in Black Hawk CO

Your LO does not understand that is the issue but it is in black and white on the link I posted.

Black cabinet hardware and changing to a black sink to match the other appliances would look nice though and wouldn't cost much

Go underwrite with that and tell me how in the black you are.

I feel like everyone is stepping away from the beige and gray and gravitating towards the white walls and black trim etc 

Then it is black and white....they either meet the criteria or they dont.