Cool cool... I just thought that if its discolored, then theres some dirt and grime deep in the base...
Im going to hotwax it and pull the wax right away.. I noticed the wax was getting dirtywhen it melted with my iron.. so that should help.
There is dirt and stuff embedded in the base of the board... but you'll never clean it all... you'd have to heat it up and then try cleaning it out with scouring pads and other abrasive cleaners... even then I have my doubts as to whether the base would ever be the same.
The problem is that you rode over that stuff... meaning that it was jammed into the base of the board.