Also, part of the problem with New Coke was the test methodology was fatally flawed.
They entirely used "sip" tests. Have testers take a sip of this beverage. Now have them take a sip of this beverage. Which do you prefer?
People don't drink soda by the little sip. They usually drink it by the glass or cup full.
I haven't ever seen a review of the methodologies used, so I cannot speak to that.
It seems fair to mention two (and a half) things:
1) With respect, I have rarely seen anyone drink, say, and entire 12 oz can of soda in one long pull. They take a swallow or two, and put the can back down, so while it may turn out to be a flawed methodology, it seems a reasonable guess. One usually learns of failed testing methodologies when the testing fails to accurately test - learning how to test is trial and error.
1a) I know there's issues with comparison tests if you don't do the comparison
immediately. You aren't going to get a reliable comparison if you expect the tester to have to go through two cans of soda before giving you a response.
2) I'm sorry, but you don't get accusations that the formula change was a "communist plot" out of using a sip test over some other testing protocol.