From The Telegraph:
Tea really does taste better from your favourite cup
Dr Tom Stafford, psychologist from Sheffield University, says a person's brain is trained to believe the daily ritual of making coffee or tea should be done in a certain way in order to derive maximum enjoyment.
He said: "Drinking tea and coffee is very ritualistic and people become very addictive to the way they want their brew made.
"Caffeine is very much a drug of reward and like any addict, people develop passions on how the drug is delivered.
"Where ever there is drug use then rituals will always develop.
"The long association with the delivery of a morning cup of coffee or tea people genuinely think it tastes better out of a particular cup.
"It might be irrational or arbitrary but it's absolutely true. Your daily brew tastes better from your favourite mug.
According to research, 65 percent of Brits have a favourite cup or mug they use for their morning cuppa.