Coffee's great hot, and it's tasty iced—but anything in between is just disgusting. While there isn't a ton of concrete research into why that is, experts provide Life's Little Mysteries with three plausible theories. First: It could be because of the way our taste buds work in different temperatures. It seems that when food is particularly hot or cold, we don't pick up on certain flavors. So perhaps our tongues simply aren't picking up on coffee's bitterness when it's steaming or iced.
Another possibility: We may like hot coffee in part because of its smell. "Odors influence coffee flavor very strongly, and it is easy to go from sublime to horrible," notes a psychologist. Hot coffee offers a stronger scent than room-temperature coffee. Lastly, it could just be a matter of distraction. "Hot coffee may force you to think about temperature, which is a bit of a distraction from its bitterness," the researcher adds.