A study says so; it must be true:
In general, how people perceive taste is influenced by many factors unrelated to the actual food. Past studies have shown that the color of the plate, the price on a bottle of wine, and the verbal description of food can affect people’s enjoyment of dishes and drinks alike.
To see how hot chocolate enjoyment was affected by cup color, Piqueras-Fiszman and her colleagues asked 57 participants to rate samples of the same delicious beverage in four colors of plastic cup: white, cream, orange and red. (All cups were white on the inside.)
Read more about that cup colour vs taste test for hot chocolate here. Seems like it is time to update that Charles Dickens quote.