Whether you're too lazy to wash out your office coffee cup each day or you're just attached to a particular mug, you no longer have to be embarrassed by the days-old stains in your mug. Actually, there's no reason to wash your coffee cup daily, unless you're sharing it with others.
According to infectious disease expert Jeffrey Starke, it's perfectly safe to reuse your mug a few days in a row, especially if you drink your coffee black. If you're using cream or sugar, you might want to rinse your after your morning fix, but otherwise, there's no need.
Most of the germs on your coffee cup actually come from the person who was drinking it, and even if you're sick, it's very difficult to re-infect yourself.
So good news for frequent coffee drinkers, and for those who just like to stick to the same mug-- you can enjoy your coffee without doing a dish all week!