There are metalized and carbon dust and it could be the way of the construction
to trap'm to create lower resistance routing...
Or as said, the high voltage ignition wires may have the carbon filled fiber glass
strands compromised...so it finds a lower resistance path via the surface of the cap
On the engine oil mist...haven't heard of that in a long time...but
true.
Even poor lube to create that wobble and the old fix was to grind a
small groove on the shaft to allow some oil to seep down to the bearing
Dist's do wear out too and why one reason I use the best lubes can get
so help prolong the life span of this kind of stuff