Good Airbnb owners who self-manage are meticulous with their systems and also understand that the aesthetics equal cash on STR circuit.

It's not a deal breaker.  

The exception is the second circuit. 

Start Small and make your big mistakes Early.Deal breakers- market, finance, zoning, footings, road type, water/sewer availability, Storm sewers, Storm retention ponds.

Start Small and make your big mistakes Early.Deal breakers- market, finance, zoning, footings, road type, water/sewer availability, Storm sewers, Storm retention ponds. 

So I removed the boxes ran the circuits from the new electrical panel around the house, through the basement and attic, then fished the wires through the walls.

Also what if you make an offer and during the due diligence you find out information that is a "deal breaker" for you, what do you do then? 

It's got updated circuit breaker panels, but it still has some KnT.

I didn’t know paint remediation was a potential deal breaker around here, but I did promise myself that my first property would be new-ish (~1950 and later).

Seriously, though you can get a "Non Contact Voltage Tester" for $20(name brand tool) from a home improvement store and only $6(cheap no name brand) at Harbor Freight tools....it is a very easy tool to use, that when you pass it over the black(hot) wire will light up and make a buzzing sound, if the line is hot/charged.But, as others have mentioned, you may do what I have suggested and the line appears uncharged, BUT, it is connected to a switch at a breaker box or wall switch that may accidentally be turned on and then create a very dangerous scenario.I personally do not like mystery electrical wires!