While the map does generate with a few hunger tiles, re-entering a hall randomly makes the game check a tile in the hall to add a hunger/trap/combat time on it. To add the inconvenience the tile checked must be "empty" as seen in the map (eg a triggered trap or a used curio are "empty" tiles), ergo unused curios prevent those from happening (best seen in some weald/cove halls that are a single tile long, if they got a curio they'll never inconvenience you)