So you are tired from traveling and the flight attendents are going around with the beverage cart. You want a pick-me-up. But there are reasons why you shouldn’t get coffee from this cart.
There was a Reddit thread asking for secrets from people who work for airlines.
Some of the responses regarding coffee were that sometimes the hand-washing water is next to the coffee water which are both next to the container containing the blue disinfectant where the lavs are dumped.
Another person commented that no one washes the container. They didn’t even have cleaning supplies if they wanted to.
So unless you bring your coffee on board with you, you are out of luck for that good cup of coffee!