I can tell the difference, but I couldn't tell you which is which.

This usually pops up around Passover, when Coke switches to an all sugar formulation for reasons I'm unqualified to explain. It's an "oh hey, this Coke tastes different", I'll check the label, and see that it's sweetened with sucrose instead of HFCS.

I'll handwavingly claim that this is close enough to a blind study/anecdote as I'm not Jewish and haven't a clue when Passover falls. As I buy cans, not bottles, it's not the yellow caps giving it away either.