Consider this for a minute: There are many things an editor does with his day. Many of them, I have no doubt, are irritating, dull, and feel pointless (the inevitable conversation with the writer who hates his cover, lunch with the one guy in sales you just can't stand, &c). Some of them, I expect, are satisfying and pleasant (learning that production has really nailed the look for that book you're excited about, writing a real good piece of back cover copy, &c).
But the kicker, the real thrill, is finding and developing a new writer no one has ever heard of who will, either right now or with some work, set the sf world on its ear. And just where do you imagine they find a new writer no one has ever heard of?
Of course most of slush gets sent back after a cursory glance; most manuscripts they see can be safely rejected with a cursory glance. If the first sentence is, "cosmo flexsed his mity thews and lifted his gratesword's into the air of nefteron thinking of all the womin he wuld have after defeeting the evil tyrant glog and sacking the town in revenge for the deth of his famly when he was a small child in the wilderness," then a trained professional is able to determine that this fellow is not quite ready to hit the stands.
But if a quick glance is not enough to determine the story is junk, guess what? It gets more than a quick glance. Finding something good in slush, discovering that gem (or, perhaps even better, something that can become a gem with some work), is what those weirdoes live for. Well, that and making a really perfect one-line smack-down to a writer who's starting to get cocky.
Send it out. Keep sending it out. Ignore all the bullshit tricks for getting past the slushpile. If it's good, someone will buy it.