I do it all the time! I rarely replace plugs - just clean and regap. I've been doing it for over twenty years for all the cars I take care of with no ill effects on performance. I replace the plugs when the center electrode is worn too far. The money saved has added up over the years.
I clean plugs by grit blasting. Besides removing all the deposits, the key point is to clean the insulator nose around the center electrode. Deposits on the insulator can provide a leak path for the spark. Then I finish-clean the plug by wire-wheeling the threads and inspect around the insulator to make sure there is no leftover grit trapped inside.
Just a reminder - don't forget to put a thin coat of neversieze on the spark plug threads before installation.
95 E320 Cabriolet, 131K