No, the porcelain really needs to get cleaned. And grit blasting is the only way. I sometimes wire brushed deposits from plugs during the leaded gas/12,000 mi tuneup days, but I don't think that's a good idea anymore.
I'm fortunate that I've always had a grit blaster at my disposal.
I've seen a tool made specifically for cleaning spark plugs. All you need is shop air. It's basically a hand held grit blast gun with a bag that recycles the abrasive. J C Whitney may have it.
95 E320 Cabriolet, 131K