Yeah, I keep some Hoppe's around for powder fouling too, even though I don't use many dirty-burning powders anymore. The smell is part of it, but mostly I just like to have one of the bottles on my bench!
We buy Hoppes #9 by the case at work as Lycoming specifies it to removing carbon from injector nozzles! Tempest also specs it for removing fouling from fine wire plugs (iridium plugs). I put it in a beaker and run the stuff in the ultrasonic cleaner and speeds it up by about 1000%.
