i have used my ultrasonic cleaner on some pretty messed up motorcycle carbs with excellent results.
the ingredients i put in my personal mix that goes into the water breaks down , varnish ,crud , rust , oxidization , corrosion, and almost any element that is found in a clogged up carb, it does not effect the zinc plating on most carbs .
as posted , good probing with wire and the majority of carbs i clean are in perfect working order when reassembled.
with that said , people use cheap china kits , they break down and clog the carb , in turn making them impossible to clean no matter how good you are at carb cleaning.