This exact thing happened in the wine world in 1976 during the "Judgment of Paris" wine-tasting event. The top wine critics in the world did a blind taste test of the best French wines and a bunch of unknown California wines. Naturally, everyone, including the critics, thought France would win hands-down. California won, shocking everyone. Before revealing the results, the judges were asked whether they thought the California or French wines had won. They all assumed that the wines they rated the highest were French, claiming they could tell which was which even while blinded. The interesting thing isn't so much that California wines were good, but rather that the professional judges couldn't tell the difference in a blind taste test.