I'm using Motul 800 so I always get some smoking. The spark plug is a bit grimy but no fouling issues. I've used the same plug for four years. One benefit of a high flashpoint oil is that repacking the muffler is a breeze. The core stays oily; no burned carbon plugging the holes.

Change the plug for giggles. Every time I've left it too long its got crisper on change. Never fouled one.