I take a quality vs. quantity approach to people's spelling and grammar. I'll give an example: on a certain website I won't disclose the name of, there was a video entitled "Get Want You Want" to be fair, none of the words in that phrase are actually mispelled but the misuse overshadows that small merit. Seriously, the sentence has four words in it (three if you count the repetition of the misused word), and already by the second word the thing's gone awry. Put simply, if your post is a paragraph or two, I might forgive the occasional "tEH" or even "definAtely", but if the post (or especially the title of your post/thread) is, for example, "Definately teh wors tgame of al ltiem" you've lost respect from the word "Go".
Final thought: if you're going to talk down to someone, do so from a HIGHER place, or at least someplace with spellcheck.
Final final thought: I'm actually drunk writing this right now, and even I'm re-reading it to make sure all's well.