cleaning spark plugs?

Anyone try using an ultrasonic tank on fouled plugs? Not sure what the best cleaning fluid might be and you need to be very careful using any solvent in one, but the cavitation does a good job mechanically cleaning carbon fouling off of just about everything I've ever tried from rifle brass, mechanicals, and carb parts. Simple Green would be a safe starting point. You could easily fab a plexiglass board to hold just the threaded end vertically in the solution if you were so inclined.
I don't currently have a running car to try it out on but will hopefully be able to report this fall.