Wanna see a fried Bosch Platinum anyone?
I have been having some minor performance problems with my 1984 500SEL. I chased a few things down without much luck. Out of my personal and professional love of arc phenomena, I read this thread. I bought semi-fancy Bosch +2 platinums last summer, and have clocked about 4000miles since. I pulled one last night to check their condition. Aside from looking a bit rich, the gap looked really big. It took a few minutes then I figured out why. Because the thin-wire platinum center conductor WAS GONE. Turns out every plug had no center electrode left. They dun arced plum off. I am going to take a picture and post so everyone can see. Eight "period" plugs later, I'm lightin' up the rear end.
Other than that, I think there is probably a big difference in what plugs work well in a 1984 5.0L and a 2002 5.0L engine. In my understanding, a 2002 engine is far more efficient at burning the charge (swirling, turbulence, squish bands, fuel mapping, etc.) therefore less plug damage via unburnted fuel.
Incidently, unless a getter (secondary electron and/or hole donor) is used, ALL electrodes will "plate" off, so to speak. The arc is stuff going from one side to the other.