I don’t have a lot to add to Tessa’s excellent analysis of “Donkey Skin,” apart from a few thoughts on the convention of female beauty in fairytales.
(And the aside that my child-self was absolutely appalled when the king agreed to have the donkey killed.)
The story of Donkey Skin has some interesting stuff going on regarding standards of beauty. Typically, when princesses are persecuted in Western fairytales, they don’t have much recourse apart from their sweetness and their stunning good looks. Often, they’re asleep somewhere, showcased to best advantage (glass coffin, roses). The going trend is Breathtaking and Sedated, rather than Hardworking and Ugly.
The exception to this is a whole subset of Cinderella-type stories where the worthy girl is relegated to servant class despite her noble birth. From a young age, most of us are familiar with the idea that Cinderella is not immediately recognizable as the girl from the ball because she’s not very clean. Donkey Skin, however, is filthy.
Not only is she a member of the working class, she’s downright repulsive. People in the region won’t even let her in the house, which is a level of unappealing seen more often in male victims of enchantment, like the Frog Prince or the Beast. In those stories, the maiden must recognize her creature’s inner-beauty in order to break the spell and reveal a handsome prince with chiseled features, straight teeth, and minimal body hair.
However, despite a similar setup, the way the story of Donkey Skin plays out is very different. The prince falls in love with her, but—as in the case of Cinderella—he doesn’t encounter her in her greasy black animal hide, but clean, made-up, and wearing the most impressive dress she owns. There’s no question of his coming to appreciate her inner-beauty, because her outer-beauty is blinding (in this case, literally—her dress is made out of the sun).
There’s a gender-studies dissertation in all of this, I’m sure. But for now, quick-and-dirty lesson is, even when the girl in the story is ugly, she’d better be shockingly beautiful, because she only gets one chance to be glimpsed through the keyhole. She has to make it count.