FESS Fesshole HOLE @fesshole
We had a cappuccino machine, I thought my wife kept cleaning the crispy dried milk off the steamer spout, she thought I was doing it. A year later, after coffee every morning, we found out the cat was licking it off when we were at work.
On the health side, it CAN still lead to harmful bacterial growth. Whether that bacteria will end up in the drink probably depends on the machine itself and where the growth happened, but it's still not great to have around.
Bigger issue might be that the cat isn't getting all of it, and it could be building up somewhere