Whenever I think about how fairy tales fit into the context of their origins -- say, the days of the Brothers Grimm and the centuries before them -- the definition of fairy tale changes for me. You know, how the unfamiliar trappings of royal kingdoms and castles, of forests in which one might get lost, stoney wells one must visit daily with a bucket to lower into the mysterious depths, looms on which one must work to create fabrics (wishing there were some magic way to speed up the process), and so on and so forth, were contemporary descriptions to the original tellers and listeners, not fairy-talish settings from Disneyland... What made the tales "fairy tales" gets a lot simpler in that context.
A few modern cliches might be removed from the definition as well -- like happy endings, family values, and poetic justice always meeting our sensibilities. We've all come across some of the grisly older versions of the most popular Disney stories. Cinderella's sisters cut off their toes and heel, respectively, trying to fit into her shoe. Hansel and Gretel were sent to get lost in the woods by their own mother as a cost cutting measure. When Snow White's mother came to her wedding at the end of the story, our pure heroine had her tortured to death. I seem to recall Pinocchio smashing Jiminy Cricket without a second thought. You get the drift.
And, a few modern understandings must be adjusted -- the pure fantasy of the giant beast in the woods waiting to eat you was not pure fantasy in the old days. Some believed in fairies, and some did not; but who was sure? Some believed powerful creatures from other worlds might visit humble folk in the country, and some did not; but who was sure?
I find it hard to separate our notion of "fairy tale" from what served as the spec fiction of the past.
