Do not make a note about what they say, study what they do!

There's a great lesson behind what Allen Rosenshine says "Do not make a note about what they say, study what they do!".
Pepsi Co. started in 1975 a consumer research designed by Bob Stanford approaching consumers in the field, giving them a choice between two unmarked bottles of cola, and asking them to choose which was better. People chose Pepsi and they decided to film these tests with a hidden camera launching a new campaign called the "Pepsi Challenge" which showed a clear preference of Pepsi over Coke. The local campaign led to a rapid increase in Pepsi market share.
In March 1981, Robert Goizueta was appointed Coca Cola Chairman driving a critical movement that shocked the USA and worldwide Coca Cola addicts. Bad news seemed to be hitting Coke from all sides and Pepsi loyalty relentless rose. Goizueta called a five-day worldwide manager's conference where he had an important message to deliver: We need to debunk the long cherished theory that Coca-Cola's success comes from its marketing expertise. If you want to be the leading brand, you can't have a taste disadvantage that is proclaimable.
In 1984 they created a new Coke that was sweeter, smoother, less fizzy, and with a soft, sticky taste due to a higher sugar content versus the exclusive use of corn syrup in the original. Tested in blind taste tests the new formula beat Pepsi by a relevant margin. The team had found a new Coke. On Friday April 19, Coca-Cola's public relations dpt delivered an invitation to the press for an upcoming conference to announce that Coke had a new formula, stunning Coca-Cola's world.
Goizueta's father spoke out against the switch, jokingly threatening to disown his son. This day was named as "Black Tuesday".

Rosenshine's words:
"People do not drink a liquid, they drink a brand, and the one who drinks Coke only wants Coke, even though it is not that sweet. If they do the "blind tasting", they choose the sweetest one but, when buying, they just prefer to see their favorit brand".

Coca-Cola company escaped collapse coming back and re-launching the classic Coke...perhaps just Coke can make this kind of mistakes and strengthen acceptance.