Loch Du (the bottle's not in front of me and I'm not certain of the spelling) is a black single-malt that is sold in a clear bottle. In the glass it has the appearance of black coffee. It has a cool peaty nose, a dense oily texture and a rich complex flavor that starts out with a spey-like malt sweetness warming into peat smoke and wood tones. The mid and aftertaste betray the nature of the black color and thick texture: charcoal from the well burnt insides of the casks. This charcoal note becomes more and more prominent as you work through the glass becoming a bit cloying, in my opinion. Not to knock the quality of what is clearly a carefully made scotch, just not one of my favorites. My question concerns the stains. I find my teeth take on a brown tint after a good dram and the napkins get some stains which are of a brown coffee-like hue. Anyone have any experience with this unusual scotch? Are these stains permanent? Any advice about getting rid of them from teeth and from linens would be appreciated. I'd be freer with the stuff if I had a strategy for the "side effects".