I do not have an inspection camera but recently when I looked through the spark plugs holes, I could see the same images.
But I was running on LPG for almost 12000 miles then, so I thought they would be clean. On the other way, I had serious starting problems for two weeks, so do you think that the pistons could be clean and got this dirty again because of those two weeks of starting issues? The old GM spark plugs, all of them were dry black. With new spark plugs, the starting issues disappeared. But now and then I have the P0171 System Too Lean Bank 1, before and after the spark plugs change.
What's your thoughts?