Trying to figure out what editors want is like trying to prove that someone is a witch. If your story weighs as much as a duck, then it floats, and if it floats, it gets published.
If your story weighs more than a duck, they send it back with a form rejection. Not even a full-sized piece of paper. A quarter sheet, if you're lucky.
But if it weighs less than a duck (and thus floats), then your story is good but not right for the magazine. Or they just published a story just like it. Or they enjoyed it, but not enough to buy it.
If you're lucky, you've only waited a month to find out. More likely, it's taken three months.
Lately, I've seen a number of magazine guidelines that state something to the effect of, "the longer we have your story, the better your chances because we like it and are trying to make up our beautiful minds whether or not we want to publish it."
Only this isn't always true. I was just looking back through the record I keep of all the places I have sent stories, how long they kept them, and their responses. I've got stories that were out 5 months, 6 months, 7 months, 10 months, a year, only to receive a form letter rejection. You sit and wait month after month thinking, hey, this story might have a chance, and then one day you open your mailbox and there's your SASE with a tiny slip of paper about the size of a bookmark that says, we don't have time to respond personally to every submission.
Many of these magazines also don't accept simultaneous submissions, so your story ends up in limbo for months. If you're lucky, you get to send your story to four people during the course of a year. Break the rules and you better pray you don't get lucky and have two magazines accept the same story for publication - you'll be blackballed for life.
If only more magazine editors could be like Gordon Van Gelder at Fantasy and Science Fiction, or Chris East at Futurismic. Neither of these two fine gentlemen has ever published a story of mine, but neither have they sat on my stories for months on end only to send me a form rejection. The Magazine of Fantasy and Science Fiction is one of the grandaddies of the genre. They probably receive hundreds of submissions a month, but not only does Gordon always respond within a month (and usually within 15 days), not only has he read every word of every story I've ever sent him (even the really long ones), he has never once sent me a form letter rejection. And to top it all off, he puts together a great magazine.
So if Gordon can do it, why can't everyone else?
If you can figure that out, you'll know why ducks and witches float.