I have found a definite downside to the unusual themed anthology submission project. Often times, the stories that come out of these calls for submission are quite specific. This isn't to say that they fall completely outside of all known genre fiction, but they do tend to require certain content or stylistic considerations that make it very hard to find a home for them outside of the originally intended market.
There's a part of me that wonders if this is the price for attempting to give market considerations a significant vote in the deciding-what-the-hell-to-write-next process. After all, shouldn't writing (and all art-making, for that matter) be about creating the work that bubbles up from the very depths of one's soul or some other such ideal?
I call shenanigans on that concept. Of course, you need to feel a connection with what you create. If one's goal is to reach, entertain, and move potential readers, you need to create work that has a chance of reaching those readers. Market considerations are a perfectly reasonable element to making sure that the work we create has a fair shot and fulfilling its purpose.
If the goal of a story is to simply entertain the author, then no such consideration needs to made. Hell, I see little point in writing it down to begin with. If the only purpose of a story were to entertain myself, I could just sit in a chair and imagine the story while grinning like an idiot and freaking out the people around me...come to think of it, that could be kind of fun. But I digress.
The far more important writing lesson that I am gleaning from recent failed attempts at finding new homes for rejected stories has to do with editing. If the story at the core of a piece is solid and interesting. If the characters speak to me and the premise delights me and the settings are interesting and the prepositions adequately relate the proximity or relationship between nouns in the text, then there is no reason to cast the piece into the forgot corners of my back-up drive.
Still, this is a prime opportunity to see that editing is not always about polishing prose and correcting punctuation. Sometimes and edit will require evolving the piece into something new(ish). A story written specifically as a "dark fairy tale" is going to have a certain style and cadence consistent with the fairy tale genre which makes it wholly inappropriate for a straight fantasy market, regardless of how well the content of the story may fit.
These are hardly revelations to me (or, most likely, to you), but it's nice to occasionally have these kind of craft-centric truths driven home in a more tangible way. Having a rejection letter stapled to your forehead is a great way to take yourself from merely knowing something to actually Knowing.
And now....to go apply some reinforced Knowledge!