Since late 2009, we've sent out over 130 paid critiques of rejected stories, and only two have generated what I'd call unhappy responses. In both cases, the authors felt I'd either missed or misinterpreted critical information in the story. And in both cases, the stories were based on real life to such a degree that I'm not sure either contest entry qualifies as fiction. I don't think it's a coincidence that my most negative reactions came from critiques of stories based on real life.
For one thing, it must feel kind of insulting to be told we don't believe your story that really happened. There's no solution to that problem, though, because On The Premises is a fiction magazine that emphasizes creativity, so we're going to keep assuming that the stories we receive are at least 90% made up. (If you want to write about your real thoughts and feelings, then give your real thoughts and feelings to made up characters and put them in made up situations that would evoke your real thoughts and feelings.)
To show why stories based on real life can often fail, I'll transcribe a conversation between me and an imaginary author who wrote an imaginary story called "Sister From Hell." (We have never received any story with that title, or any story similar to the one I'm about to describe.)
ME: ...so to summarize, we didn't believe the extreme behavior change shown by the narrator's sister at the end of the story. Since the whole story hinges on that change in behavior, it's fair to say we didn't believe the whole story, and that's why "Sister From Hell" didn't make the final round of judging.
AUTHOR: Well of course you didn't believe it. She fools everybody.
AUTHOR: The story's based on my real sister, who fools everybody into thinking she's the nicest person in the world, then stabs you in the back.
ME: Okay, but we're talking about the narrator's sister in "Sister From Hell."
AUTHOR: I'm the narrator! I'm writing about me and my sister.
ME: First, if we'd known the story was non-fiction, we'd have disqualified it from our contest. Second, we're not concerned with your real sister here, we're concerned with the character as described in "Sister From Hell."
AUTHOR: I just told you they're the same thing.
ME: Look, you have a great deal of personal history with your real sister. How did you learn she's lying when she's acting all nice to everybody?
AUTHOR: [Gives many long, detailed examples of sister's deceitful behavior, and the clues the author discovered that proved the sister was lying.]
ME: Great. The problem is, none of that information appears in the current draft of "Sister From Hell." The story we received spends ten pages showing the narrator's sister performing such selfless, kind acts that we were ready to nominate her for sainthood. Then on page eleven she burns down an orphanage and laughs at all the dying children.
AUTHOR: Okay that never really happened, but it's the kind of thing she'd do if she could get away with it.
ME: My point is, there's nothing IN THE STORY to make us believe she's anything except what she appears to be: nice, sweet, etc. Not until she burns down an orphanage. To us readers, that act came out of nowhere. I think the real problem here is, you know your material so well, you forgot that we DON'T already know it. If we knew all along your sister was a psychopath, "Sister From Hell" would probably have worked better for us. Since we didn't know that, the last part made no sense to us.
AUTHOR: My gosh, you're right! [Author goes on to write best-selling novels, win a Pulitzer Prize, and publicly credit me as a mentor, thus helping me teach creative writing somewhere. Like I said, the author's imaginary.]
I think the biggest problem with the advice to "Write What You Know" is, it's too easy to forget your readers don't also know it. If you write what you make up, you'll ask important questions about your characters, plot, and story's world because you probably don't know the answers to those questions either. As you develop the answers to those questions, many of them will appear in your story, probably because that's how you're coming up with the answers. If you already have all the answers, you might leave out something your readers will need to know.