I stopped trusting before you, but still had problems..
Everything checked out properly on day one of a two day hotel gig. My brother flipped on the main breaker in the distro on day two, instantly almost all the fuses in all the FOH and monitor mix gear blew, the amps were undamaged as they were all turned off, but we always just killed the main breaker rather than turning off individual front end stuff.
Turns out a rookie house electrician had untied our tails after we had left, thinking we were loading out in the morning, then realized we were in for two days, then re-tied us swapping a hot for neutral.
Fortunately he had logged his action so we were able to get some money for the stuff that burnt up instead of blew fuses.
You just never can tell what will happen from day to day...
Art
Years ago, we used to have an old dimmer rack that was 100-A single phase. For a particular show, we handed the tails to the city electrician, or "electrician" as it turns out. The tails were the normal color for something like that: Black, Red, White, Green.
I got kind of a weird vibe from the guy, so I felt more inclined than normal to double check things. Turned on a breaker for a single edison recept on the distro to meter and had 208v from hot to neutral, and neutral to ground. Mr. "electrician" was nowhere to be found. We had to get moving with setup so I went to check the panel he tied us into. I noticed that there were only 3-pole breakers in there. I figured he probably would have just used 2 of the 3...but whatever. I pulled the cover off and found that he landed the Black, Red, and White on the 3-pole breaker, and the Green with the other Whites on the neutral bar. Fantastic. I moved everything around where it should be, and the show went well.
Up to that point, I *usually* metered before we turned anything on...especially if I wasn't the one making the connections. Since then, I've done it every time, no matter what. I also make it a point to check voltages periodically while the system is fired up and running before showtime. Doing this, I've found the occasional loose connection with enough time to take care of it well in advance of the opening number.