I don't really care, unless the medium by which the improper grammar is presented is something formal or school-related. My senior year of high school, I was a teacher's assistant. I once graded a five-page essay in which the writer wrote sentences like "i dont think u shuld do stuff like that cuz its bad", and it was very difficult to grade it for content. When it comes to a setting where you should be using proper grammar and mechanics, I am beyond a Grammar Nazi, I'm a Grammar Eldritch Horror. There are a few things that irk me more than anything else, however, and whenever I see those I have thoughts that would make Lovecraft and Bosch shit their pants.
Furthermore, the whole "hi i new plz give gold" is kind of irritating, but only for the frequency I hear it. If they aren't native English speakers, that's a different thing.
The difference between British English and American English kind of throws me for a loop when I first see it, but I always catch it before I try to correct it. Again, with non-native English speakers, that's fine because learning a language with as many contradictory rules as English is difficult, especially when you already speak a different one, but when somebody born and raised here mutilates it, it bothers me.