Okay, so this is a technique that no one else has mentioned that I know works and leaves no scratches.
Get the pipes nice and warmed up (hot), then use a piece of soft wood, balsa or anything semi soft. Stick the wood against the pipe and the wood will burn a little, just like wood burning, but it will pull the marks right off the pipes and into the wood.
May sound funny but it is easy and it works better than anything when other ways have failed.
I've used the oven cleaner sprayed into a cloth as soon as stopping the bike, and it mostly works, and I've used the razor, and it is scary, but mostly works, and the never dull, and it mostly works. All kinds of chrome cleaners and they kinda work too. But this burning wood idea sound pretty cool.

Thanks for the great tips. I seem to be way to fidgety. I have the heel guard on my floor board, but then I just use it sometimes as a heel rest, and the inevetable black mark on pipes happens. I've also been known to melt the strap to my camera bag on them. Melted a couple of microfibre cleaning cloths too. So, my poor pipes have been used and abused. Good thing there are folks like you out here that can help us heel mark challenged riders out of the black rubber jam, so to speak.
