This argument has an actual referee. The US Department of Agriculture warns that cooking an animal with its body cavity filled with stuffing presents potential food safety hazards, because the stuffing can still harbour bacteria even when the meat around it has reached a safe temperature, and it recommends cooking stuffing separately and not buying pre-stuffed birds. The practical problem is the whole dispute in one sentence: bringing the centre of the stuffing up to a safe temperature usually means overcooking the meat surrounding it, and the flavour the inside-the-bird camp is defending comes from precisely the juices that create the risk. The vocabulary is a clue to how regional this all is. The word stuffing has been in English since about 1538, while dressing came into American use much later, around 1850, and the two words are now applied to the same dish whether or not it has ever been inside a bird. People are often arguing about a method, a word and a family habit at the same time.