I care about it all.
I mind if I make a typo (I don't lose sleep over it, but it irks me mildly).
I almost never make a spelling mistake - I'd say 99.9% of stuff I post is spelt correctly.
Grammar...mine's good, but I write as I speak, usually.
And text speak is just horrible. Why use it when you have a whole keyboard at your disposal?! It's not actually even quicker when texting if you use predictive text!
Having said that, I would never leap on someone (apart from somebody I know to be a fellow pedant ) for misspelling something. And if a post is in text speak, I just don't bother reading it - I can't be arsed. Same goes for "unparagraphed" posts - like wading through treacle, those!