I heard of vodka as a 'clean' drink from a Russian friend of mine. As for me, I think clean relates to purity of brewing/fermentation. So I'd have to say a beer can be clean. But then, I'm sure Tal would have beaten me at chess so maybe I'm mistaken.
Oh, it turns out our dear Tal never touched wine or beer, but drank only the "clean" drinks, says his wife, Angelina Tal:
"It's known that Tal was a chain smoker. He could smoke several packs during just one game..."
"Yes, Misha would smoke two packs of Kent (he smoked long "deluxe" cigarettes) a day. He had a habit to smoke a quarter of a cigarette, then throw it away and get a new cigarette. So actually he smoked just half a pack. During the routine medical examinations, the doctors said that he had very clean lungs and an infant's liver. Hard to believe? He drank only clean drinks - vodka, whiskey, and never touched beer, wine or cognac.
http://blog.chess.com/Spektrowski/an-interview-with-angelina-tal
What a shame. I guess he lacked a good mentor who would recommend him a few brands of beer.
And this is the first time I hear of vodka & whiskey as the clean drinks, and beer and wine as the what, non-clean? Has anyone heard about that before?
Anyway, I knew there was something about Tal that disturbed me.