When I was growing up, Wisk laundry detergent sponsored an ad campaign that focused on "ring around the collar". The commercials always showed women struggling to remove the dirt from inside the collar of their husband's white shirts.
Those images pop into my head when I am confronted with the dreaded morning-after glass of partially-drunk raw milk. When you pour it out, you are left with a thick ring of cream at the tide line and also a cream "pancake" that was floating on top. Unless you want to focus a jet of scalding hot water on it for several minutes, you have to scrub it off. It doesn't come completely clean in the dishwasher, at least not my dishwasher.
Happily, it's the only negative thing I know about drinking raw milk.