Since apples are propagated by grafting (cloning), has anyone kept original ("heirloom"?) Red Delicious stock from before it was optimized for looks? I'd be very curious to try one!
If you know what they are, you'll probably be able to identify the red delicious flavor, mostly in the skin I think. However, my guess is if you gave one to a bunch of people they probably wouldn't recognize them as red delicious apples. They might identify them as mcintosh or something like that.