Any tube can arc or go bad. When tubes are tested & burned in, the likelihood of this happening is much less. Svetlana had some problems with some of the older versions of the KT-88.
Power 2 owners really like the Svet KT-88 in their amps. Any tube that arcs will usually blow out a plate or screen resistor. This is more common than many people realize, and is easily fixed by soldering in a new resistor. Then you are up and running again. This is just something you have to deal with if you want to own a tube amp.