Yes, Hotel liked to re-use food. I worked in hotel before. The U.K. general manager was very stingy, if someone ordered whisky, and he dranked half, just store the leftover in another jar, when someone order the same whisky, just pour the leftover and add new to another cup.
Next time, when you go anywhere like to order wine, 記得加冰. Then they cannot re-use. But the cup you drink maybe 人地飲過???