I know that the porcerlin cups don't ever need to be cleaned since old coffee just hardens and becomes part of the device. However, I've noticed that if I leave a travel cup in the car for a few days, the cup gets a funky, moldy type smell that highly influences the taste of ensuing cups of joe. I have tried conventional means to cleanse these cups but to no avail. Do I need to replace these now nasty travel mugs or is there a way to cleans the funk from within?
TIA,
TIA,