You obviously never worked on old worn out lawnmowers, forklifts, farm tractors, or kept old military vehicles running past their expiration date. According to you spark plugs never foul repeatedly. And therefore you've never heard of a spark plug Anti-Fouler, that you screw in the plug hole that is so oily it keeps fouling, it's like a small chamber to keep plug from being fouled, for a little while longer.