A couple of weeks ago I got a couple of large stains on my hood. They were yellowish in color and I assume they were tree sap stains. I went to work cleaning them off...first soap and water, then wax, then a clay bar, then bug and tar remover, then compounding...the stain stayed. So, I took it over to WagonWorks Collision center in Alexandria, VA. Turns out it was actually a leaf stain. Wet leaves sat on my car one night and the next day the sun came out and baked the leaf stains right into my clearcoat. But the boys at WagonWorks came to play. They wetsanded the stains and were able to get them out without cutting through the clearcoat. $76 later...my baby is back. If you have a tough stain I highly recommend letting an experienced body shop take a look at it before putting too much product on it.