This apparently is getting some wide pimpage -- I got to it from John Scalzi's Whatever blog -- but Justine Larbalestier has some great comments on How to Rewrite, and an earlier post on (more or less) How the heck did I write this so badly.
Two different things, two different processes. I've run into a few people who can write exceedingly clean first drafts, which also actually read coherently. I don't do too badly in the clean department, but until we install Firewire ports in our skulls and someone writes some really dynamite gateway software, pouring out the vision in your head onto the page isn't a simple process.
If you are a new writer, you are going to make mistakes. Live with it. And some of your stories, paragraphs, chapters are just going to suck. Too bad. Move on.
It's what you do with it that counts. And you do have to do something, because if you want your stories read, then it has to get past an editor. Now sometimes it feels like too many editors today don't do their job, which might be construed as editing, but that's too easy a gripe. I take the attitude that editors will take a chance on a manuscript once it gets close enough. If I can get the writing close to good enough, then we can get down to the editing for publication. Because even the ego of this writer knows that stuff is going to slip through.
On Being Appalled
I often reread a story before I send it out again. Not always, but often. And I cannot tell you how many times I've discovered some terrible typo or mangled sentence -- which turns out to have been introduced during the bleary hours of 1 to 3 am in Version 1.00 of a story. (grin) And here it is in the tenth revision.
Most people find it difficult to proof their own works. And your brain will cheerfully rewrite what's on the page as you read to either keep the flow going, or if you're the author, insert what you thought you were typing. And my first readers will sometimes play the home edition of this game and get caught up in the story and miss these blunders, too. Actually, I think this is a good thing. If you are too involved in the story to spot the flaws, that's not a bad place to be. Because the extreme alternatives are the turgid paragraphs that open REALLY bad writing where you cannot even begin to get into the story. And now you know why so many submissions are rejected by the end of the first page. (double-jeopardy-grin)
Anyway, if you're writing, you should read up on rewriting.