Sin in fairy tales is one of the themes I hit pretty hard when I talk to students about messages and subtext in fairy stories. Greed, wrath, envy, lust -- they're all there. Sin, is, of course, deeply unfashionable, and by "unfashionable," I don't mean to suggest that greed and lust and their five troublesome friends no longer beset we frail humans; after all the seven deadlies will always be with us. It's just that the concept of "sinfulness' is not accepted. We use the concepts of psychology and the legal system instead.
Yet belief in human sinfulness was very much alive when stories such as "Rumpelstiltskin" were being told at firesides, or even written down by early collectors such as Jacob and Wilhelm Grimm. As in most fairy tales, greed has a starring role in "Rumpelstiltskin." There's the greedy, bragging father, the greed of the king, the greed of Rumpelstiltskin for a child. The miller's daughter, who receives the dubious benefits of Rumpel's help is by no means admirable. Is she greedy? Yes, probably. But in the sense that many people would be in her case. Beyond her beauty, however, she is a cipher.
"Rumpelstiltskin" is one of the relatively rare fairy tales where men are more at the center of action than women. But by focusing on greed, it fits in with its sister tales, including numerous variants of the story.