I'm not actually a beta, but I was raised to see errors in text, because my mother was a copy-editor for a long time, and I can send something that I'm not totally happy with to a beta, but only when it has to do with plot or characterization, not the actual writing. So I'm totally with Souderwan. I've sent rough drafts to my beta, but only when I said "Hey, I have this rough draft of this scene, and I'm not happy with it, but I'm having trouble pinpointing what's bothering me. Can you take a look?" Then my beta read it and said "Okay, Myra, you need to fix this and this." But please, please don't send stuff to your beta without running spellcheck or something! I've seen fics (thank god, not here) that make me wonder what the writer did to the red squigglies.