I was working on a switch issue with Centaur II where the pop bumper would give multiball. I was activating switches by hand in switch test to see if there were other issues. Most switches would show multiple switch activations. Took me a while to figure out I was doing this with my shoes off and was completing the ground when touching the metal switches. I put my shoes on and no more multiple switch activations with the switches. I eventually found the issue which was a solder splash on a switch was causing a short. But it took much longer than normal to find since I was confused with the multiple switch activations when testing with my shoes off.