honestly, yeah, that procelain looks decent, but that white on the electrode, i wouldnt be too happy about, i wlaways make sure the whole damn thing is golden brown, it looks to me like you are running lean wide open and rich at idle ? you will figure it out, just dont hold it wide open for long until you're positive it's correct...
when you are checking your mixture you ALWAYS start with a brandy new plug, i even go as far as to warm the engine up then swap the plug for a new one, pull out and fly down the road in about 3rd gear wide open for a few seconds, pull the clutch, hit the killswitch and come to a stop without leting the clutch out, once stopped, then check your plug...this is the most accurate way, what everyone prior has said is correct, but you have to start with a new plug for sure !!!
probably a good idea to clean and oil your filter before checking too, you prob know, but if your filter is clogged by too much dirt or oil it will run richer and if its dry or ripped it will run leaner...
good luck !!!