I have a niece who worked for about a years as a maid in a hotel. One day when the hotel did not have water, the staff was told to use the water in the toilet to rinse the coffee pots out with.

I have seen hotel maids clean the glasses and coffee cups with the cloth they use for general cleaning.

Airplanes are no worse than restaurants, many of which have some very unsanitary practices. Have you ever seen the cook come out of the bathroom stall then proceed out without washing his hands? Ever purchase draft beer at the beach only to see the vendor later collecting the used cups and merely rinsing them with plain water and re-using them? Many bars often quick rinse out the glasses.

You cannot be overly paranoid, but try some reasonable precautions.