125-200cc Cleaning fouled spark plugs?

I grew up riding a beat-to-hell XL100 and Trail 90s where fouling plugs was part of the starting ritual. I would clean them using the plug cleaner above, and then hook them up to a miniature electrical transformer (I'll have to ask my dad what exactly that thing was) and burn them for a few seconds. They would work fine until the next time I tried to start the bike cold.