I am no wine expert. My understanding is that the way the wine industry talks about champagne (by which I mean sparkling wine from Champagne—forgive my idiosyncratic-but-consistent use of capitalization) is largely at odds with how we employ champagne in mixology. In mixology, the overriding concern is sweetness. In recent times, brut is obviously the most popular, to the extent that some of the non-brut champagnes seem vanishingly rare in the market, and any drink that calls for “champagne” is presumed to be require brut. Grapes, vintages, and other blending and production factors are almost of no concern to drink mixers, even the point where people blithely substitute any not-sweet sparkling wine for actual champagne without giving it a second thought. (These days in NYC that seems to most often be prosecco. Ugh!)
Further complication: it seems that in the 19th Century, maybe even up until our Prohibition, nearly all the champagne exported to the American market was vastly sweeter than even today’s Doux. Wikipedia says as high as 165 g sugar/liter! And that for the domestic French market was even sweeter still. It was all (?) dessert wine, except for the English market, which merely liked it sweet (today’s Doux levels), not saccharine. Where does that leave the Champagne Cocktail, Champagne Cobbler, Champagne Julep, Champagne Sour, Imperial Fizz, Prince of Wales, etc? Were they wildly sweeter drinks, and we make them dryer now, and that’s all there is to it? Or are we maybe missing something? (I question because while Old Tom Gin may essentially be sweetened dry gin, I find that somehow significantly underrates it.)
And how do we feel, today, about the generalizing of champagne? I know it’s nothing new—champagne has always been supply-limited. The stuff is damned expensive. And yet, my impression is that there remains a significant difference between the real stuff and all the ostensible substitutes, despite two hundred years of effort to reproduce it elsewhere, cheaper. If so, why?