One thing that really, really grinds my gears is people who write as if they were speaking the words. JB touched on this (i think) with his comment a few posts up and it just shows how uneducated and, frankly, retarded the poster is when they do this.
We all make typos and autocorrect can be a nuisance as well, but generally, these are isolated instances in a persons post and it's obvious they were accidental. Thus, we ignore them or not even notice as we read the post.
It's also not something we suffer from on CEO (thank Zeus). This is probably down to the slightly higher than average age of posters here and the fact that anyone posting like that would be torn to shreds faster than a lamb at a Tiger Tea Party.