1. SF is much better than fantasy, and will save Western Civilization besidesNo, wait, sorry. Those are the nonfiction topics verbotten at Clarkesworld. With all due respect to anyone trying to put together a genre magazine, what purpose exactly do these guidelines serve? You're an online magazine, served by word-of-mouth via the blogs of like-minded fans. You exist to serve an audience that would otherwise be underserved in the mainstream. Why get caught up in a bunch of corporatist rules and regulations?
2. Fantasy is much better than SF, and will keep society from degenerating into an Orwellian nightmare besides
3. Taxonomies of SF/F/H
4. Anything with a Venn diagram in it
5. Convention reports
6. "Literary fiction" and how awful it and its exponents are
You don't know how good someone's Venn diagram might be. It might be the most eye-opening Venn Diagram on Fantasy taxonomy, the awfulness of Don DeLillo, and how the Martian Chronicles saved human civilization ever.
And as a writer: wake-up! Publishing's dead. If you want to get your work published you can do it on your blog. Or invent your own magazine, get a URL, and publish to your heart's content.
One thing reading publishing guidelines does for me is help to better clarify the prejudices, assumptions, fixed ideas, and biases of others. Not much help in getting published, but a lot of help in understanding the "Fixed Attitude" throughline in Dramatica.