to a large extent, vodka is about mouth feel and water purity. so, if you could tell the difference between new york and chicago water, you might be able to tell the difference between vodkas. I know really good, polish vodka, when it is served cold enough, tastes differnt, but has a much different texture, than any american vodka. in russia, resteraunts will serve 20 types of vodka, all straight, and people believe that they can tell the difference