Very clever -- they've both dressed up as the scariest people they know! This is actually very deep, once you stop to think about it. Gaston is outwardly handsome, but a monster inside -- all the things Adam used to be, and the very thing which wound up ruining his life for ten years. And Belle dresses like those beautiful bar-wenches. Though they're pretty, their heads are empty, and they fall hopelessly for the ruse of Gaston's good looks. To a learned girl like here, there can be no worse fate than to not even be smart enough to realize you're an idiot. This is truly brilliant.