There's nothing like a cup of freshly brewed coffee to start the day—but we've all let a mug sit around for a little too long, only to find it tasting bitter, stale, or just plain off. So how long ...

Here's the truth about how long that cup should really sit around. There's nothing like a cup of freshly brewed coffee to start the day—but we've all let a mug sit around for a little too long, only ...