To my palate, malt flavor profiles differ significantly according to whether the malt is from continental Europe, the British Isles, or North America. It's the reason many commercial American examples of European styles don't taste quite right—the brewers have contracts with domestic maltsters and use their products for darn near everything. I'm generalizing, of course; I know many brewers pull out all the stops for their European beers, and it's definitely noticed and appreciated.
Other judges and I also notice the difference when judging European categories in homebrew competitions. I'm always careful wording my observations on the scoresheet just in case I'm wrong, but the origin of the malt is usually quite clear.