It's not perfect. The bottom and top of the cup are punctured, and the forced water tends to splatter a bit inside of the cup receptacle. Mine always has a few grounds, and the surfaces all have some residual coffee. The water doesn't run directly out of the bottom of the cup where it's been punctured, otherwise, you'd get grounds in your drink. Instead, it runs along a channel down into your cup, another place for residual flavor. Of course I clean it from time to time, but I don't do a ton of different flavors. The cleaning to get chicken broth or tomato soup out would be too much to switch back and forth.