I'm one of those instinctive troubleshooters. It must be innate, not learned. My guys can look and not see. The main thing they forget is that the (whatever) worked at one time, so it does not need to be rewired.
My favorite no-power T/S tool is my solenoid-type voltage tester and a 3-prong extension cord plugged into a known-good receptacle. You have a reference hot, neutral, and ground, at least one of which is missing.
