Any old household book should contain hints how to remove stains caused by caramel, burnt sugar, or sugar colouring - as this is what makes the L.D. so dark. The story I've heard is that during bottling, some guy pressed the button for caramel, then left his place, then another came and pressed again. Now the stuff was to dark for the regular Mannochmore sale, and instead of throwing it away, as they should have, they put it into a special bottle, invented some marketing garbage about burnt casks and such, and sold it at a premium.