Truck had been misfiring on cylinder 6, I pulled the plug and it had what seemed to be burnt oil all over it. Not sure of the cause. Pulled the plug next door to it and seemed to be just fine. I re-gapped the plug as it was a little bigger than what I had read as the norm. the truck ran fine after that. Would could be the cause of the plug looking like that? Could it have been due to it not being gapped correctly and arching off? Is it just carbon build up due to a non-running spark plug?
3.0 V6 - 5 Speed
thanks for any input given.

This is the 6th cylinder spark plug that was misfiring before re-gapping.

 

Most likely a leaking valve guide seal

On a Ford V6 #3 and #6, the rear cylinders, are most likely to have this because the oil pools at the rear of head lower side because of engines angle

For now just plan on cleaning and swapping around spark plugs in #6

You can replace valve guide seals without removing the head, but it is not easy