One of my old managers told me the story of how McDonalds was doing tests to improve their coffee. They asked people to taste-test the McDs coffee, but the cup

One of my old managers told me the story of how McDonalds was doing tests to improve their coffee. They asked people to taste-test the McDs coffee, but the cup disguised the fact that the coffee was from McDs. The ratings were generally good. When they did another taste-testing but the coffee came in McDs-branded cups instead, the ratings were bad.