Some missed the point.
I totally agree on just keeping spares. But the question was can it be done and what is the best way. I mostly replace myself. But many a time the little blaster has bailed me out of a jam at 6:00PM on Sunday or such. I would hate to inventory how many different types of plugs are in all the stuff at my place and figure what spares to keep. That would be a decent sized number. This $20.00 blaster has come in handy and does a good job if used right. Now if the only gas engine I own is my chainsaw.... then heck yeh, just buy plugs.
I think the point some are trying to make, is plugs are a very small presantage of quality equipment's cost.
The real story behind any type of abrasive cleaner, unless it's a routine clean, plugs don't crap out like that.
When a plug goes bad, it is better then 9 times out of 10 that the spark is taking a short-cut throu were the cone of the porcelain attaches to the grounding base,,,,,, not sparking. Out of those 9 that miss-fired they got that way because gas washed conductive deposits into the porosity of the porcelain. Unless you burn them out, there in there.
Even if you burn them out, some deposits stay in the porcelain and may not cause a cold start misfire, but will again quicker then it did the first time.
So if your replacing a bad spark plug, chances are that you should also be looking at the starting procedure, or why it's flooding out.