Let me answer it this way... I think less of people when they write with terrible grammar or spelling. If someone can't speak or write well but they make valid points or a good argument or whatever, they don't necessarily lose points in my eyes. I think I assume most people can write better if they chose to, like wen u type wit internet slang, so when I see that I think the person is just lazy and it tends to undercut their point. In any event, it is harder to take him or her seriously. I like to speak lazily a lot, and unless I'm giving a presentation or something of that nature, I don't think it's a problem.

yes unfortunately

It depends on what they are saying. If they are interesting, or saying something important, I'm willing to overlook the spelling and grammar. If they are dumb and boring, I won't want to wade through the crap to get to their content. And I'm more likely to dismiss them: "Well, what can you expect with that kind of punctuation??"

I'm much more critical of people who can't write clearly you know, they take about 400 words to say what *could* be said in a three-word-sentence. What a waste of time!