LOL. Was it that astonishing? I wasn't surprised at all. Certainly I should have proofread at least a little, but my habit is to just click that "I have already previewed" checkbox and click "Post".
I type fairly quickly, and it actually seems to be disconnected from the thinking process in some respects. In other words, I say the word in my mind and my fingers just naturally type it. The finger muscules seem to have a memory of their own. It's that old muscle memory theory.
Thus, since I type "no" and "there" far more frequently then I type "know" and "their" I find it completely natural and logical for my fingers to type "no" when my mind thinks "no" or "know" and my fingers to type "there" when my mind thinks "there", "their", or "they're". You should see the basic grammar errors I have to correct when I proofread the first draft of papers I type. It just goes to show you how strange a language English is.
What I find interesting is the amount of people that assume I don't know the difference between "no" and "know" and "there" and "their". I guess I'm not as dumb as I look. LOL ;)
We can't see you, of course, so we have no idea how dumb you look. :) My mother (who was both a professional teacher and a non-stop teacher at home) drummed into me that most people only see how we present ourselves through the written word - and that was long before Mr. Gore invented the Internet. It's even more true these days.
What Lord Chesterfield wrote to his son 260 years ago is still true; "Style is the dress of thoughts. A well-dressed thought like a well-dressed man appears to great advantage." In today's language, I take that to mean that I shouldn't click the "already previewed" button too fast, as I also have a tendency to do! :)