there was a pretty well known local band around here int he 80's & early 90's where the guitarist had a full marshall stack on stage. his tone was smokin' good. the problem was (not for those of us other musicians that KNEW what the game was)....there were NO speakers in the 4x12's, nor was there an amp in the head. the "on" light was plugged into the wall and he had a 30 watt Gorilla miked inside the lower 4x12 cab.
I'll admit to having done a few gigs over the last few years with a Marshall head and 4x12 cab (usually a backline rig borrowed from the venue) not plugged into anything, with the actual sound being a hidden Kemper going straight to the PA.
Sometimes I take great enjoyment from fooling the "music police" (guitar players) standing at the back with their arms crossed.