Just went through a similar event about two months ago with a plastic tarp. Much worse than your boot stain. Had about four inches worth of tarp completely melted to the pipes. Anyway, I got a bunch of great suggestions, including oven cleaner, acetone, and a razor blade. Tried em all, but in the end it was the razor blade that took it all off. Can't even tell it ever happened. It's like scraping paint off a mirror, but you have to be careful not to scratch the chrome. Might be that the oven cleaner loosened it up for the razor blade, i don't know, but the razor blade thing only took me about five minutes to get it all off. The oven cleaner and acetone were a lot of work and didn't work too good for me.
