There’s a very interesting discussion going on over at Asimov’s discussion board. I will quote Mr. Dozois, but you should click on the link to check out the discussion. The bbs uses frames so I can’t bookmark the actual discussion, but you can find it by looking for the topic “The Best SF Magazine” and scrolling down.
To answer Jim and later Robert’s question, yes, it has happened that I’ve rejected something from ASIMOV’S only to later pick the same story up for my Best of the Year anthology. This may happen because the story didn’t meet the needs of the magazine at the moment, it was a kind of story I had too many of in inventory, or because too many of that kind of story had appeared in the magazine recently, but frankly it can also happen because I fucked up–when I originally read the story, I didn’t warm to it, for any of a dozen reasons, including that I was in a bad mood that day or I read it too fast or whatever, and then when I RE-read it in some other market, it strikes me as a really good story, and I smack my forehead and say “Schmuck! How did you let this one get past you?” It’s a fact, unnerving as it may be for authors, that exactly the same story can read one way to an editor one day and without a word being changed read an entirely different way to the same editor on another, it just being the luck of the draw which way the editor is going to respond to it on any given day. I’ve also had it happen with my own work, at least two or three times, that an editor will reject a story, and then a week or two later I’ll get a note from them saying that they can’t get my story out of their mind and can then see it again, and they buy it this time around. I don’t remember ever doing quite that as an editor, but I can think of a dozen occasions when I went to the typewriter (yes, I used a typewriter at that point) and put paper in it and sat down to reject a story, even started typing the rejection letter, and then found myself hesitating, and then going back and reading the story again, and almost every time I ended up actually buying that story. I learned to listen to that hesitation, as a voice telling me, “You should look at this again.” That’s an editor’s instinct, and good editors learn to listen to their instincts.
I have never sent in to Asimov’s, but perhaps I should. There is much more at Speculations rumor mill about the Tone or Mood of magazines and the drift towards the dark side.