From what I have talked to old timers, a shaving mug is flared at the bottom a bit, and inside its curved into make a bowl like shape not straight down to the bottom which would be a coffee cup. Some are obvious shaving mugs other not so much. I picked up a Homer Laughlin SM for 5 bucks at an antique store and a scuttle for 2.50 with an American eagle and flag on it.