The previous owners "upgraded" the outlets to three prong types, which is what I'm correcting. The gang boxes are also brittle and have snapped off the screw holes, so I'm replacing those if necessary. I'm hoping my activities don't disturb the wiring enough to create a hazard.
I know which outlets are properly grounded, but I'm converting the spare bedroom into an Airbnb room for events like Indy500, Big10 championship game, etc.
I suppose I could say screw it. It's not like a whole lot of travel accessories are grounded anyways.