some cultural insights
For the unenlightened, there's a wiki for "meth mouth" (don't go there if you're eating...). The reasons so many people (probably Americans) have labeled this guy a "meth mouth" are a)well obviously his teeth, but b)Meth production (and addiction) is associated with low-income types as it is relatively easy to produce with OTC ingredients. It is associated with "rural hick" stereotypes because it requires that your neighbors not live too close, since the production area smells tremendously awful. This is not a Hollywood party drug. I should add, I know this mostly from watching the news, *not* personal experience lol.
Couple other comments: @Cazzo Enorme: No we don't. Hollywood celebs? Maybe. Believe it or not, they represent a minority. Go to the toothpaste aisle of any store here and you will find a plethora of whitening toothpastes. Does that make us vain? Perhaps, but you have to brush your teeth anyway, don'tcha? Why not de-stain while your cleaning?
I also find it unlikely that, even if he isn't a drug addict, the deplorable condition of his teeth is no fault of his own.