[a_c]

There is obvious difference for a cask strength whiskey and a 40% ABV one. But I doubt if people can reliably tell a whisky is diluted with a few drops of water in a double blind taste test. I tried and failed. IMO a lot of tasting has to do with the ritual

[teruakohatu]

If you can't taste it then you are already ahead! If the few drops you add, which are free, taste the same as the expensive whisky, you are left with more tasty whisky to drink.