Haha! I tend to agree that's probably true for most people.
Some people can taste the difference (double blind and everything - I'm not sure if anyone has done the tests). I would think the water used would also make a difference.
I think with practice almost anyone can tell the difference.
It's about as subtle as the difference between velvet and silk to your finger -- I can see how you'd confuse them if you weren't thinking about it, but there's no way you'd stay confused if you paid attention and practiced.
Some people can taste the difference (double blind and everything - I'm not sure if anyone has done the tests). I would think the water used would also make a difference.