If it were me and I had a few bucks to purchase a cheap electrical tester or DVOM (digital volt ohm meter), I would buy one and check to see whether my neutral and hot lines might be reversed (for that particular outlet, wiring run, or I suppose the entire electrical system if the fuse/breaker box is miswired). If I remember correctly, this could cause what you are describing, depending on the device. Apparently, this is not as rare as you might expect, with older homes.
But I am certainly no electrician, so if one happens to read this post, please comment, lol.
But I am certainly no electrician, so if one happens to read this post, please comment, lol.