Only one factor determines if a bed and breakfast is exceptional: the quality of its brown bread.
One should not be able to lift a slice of brown bread in its entirety; it should crumble. One should have to break off one bite at a time. It should have a soft, wheaty texture, and should never be eaten with jam, only Irish butter.
Many b&bs use store-bought bread, which is gummy and sometimes stale. If the proprietor will take the time to bake his/her own bread, said proprietor will not cut corners elsewhere, regardless of the price of the b&b. If the bread is good, the rooms will be clean and orderly. There will be soap in the bathroom and a hairdryer hidden in a drawer. There will not be dust on the bedside lamp or misty strands clinging to the corners of the room.
I am utterly converted. Brown bread is the breakfast of kings.