OCD is funny, I find it amuzing when people ask me; "Why are all these in a perfectly straight line?", "Why did you touch the table 3 times with both elbows?" .
Back the the subject in question though, Carlosio, when someone puts "teh", it's probably, well in most cases, just for the sake of being silly, sarcastically if you will. In other cases, it probably is actually just a typo, if you're typing fast, it's an easy mistake to make. I've said it before, we're not writing essays for English here, we don't get graded on what we write here, we just form other peoples opinions of ourselves. If people want others to have a good opinion of them, then they should put the effort in to make sure what they are typing is perfectly clear English. If on the other hand, people aren't really all that bothered what people think of them or their opinions, then they should feel free to just type how they want to and, if that lowers peoples opinions of them, then that is entirely their problem. I'm not even sure why this is a talking point, if you just tell a member at the time of a particularly bad post, that what they have typed reads like it was written by a 5 year old, I'm sure people would start to buck their ideas up.