Improper grammar/spelling should be used only in jest, and nothing more. If you're in a super fast hurry, such as jumping in midair in a game while turning and firing at someone who is trying to take you down and would like to say something in that split second of time, then I have no issues with someone typing horribly or using major shortcuts.
But if you do it on FORUMS or in chat? Come on. You've got all day to sit there and type up a reply, and it honestly takes less time to type properly than it does to type a bunch of gibberish. Why? Because your mind knows grammar better than it doesn't, since that's what all you kids have been studying for years and years in school. So it's a lot easier to let your mind flow, your fingers following, and type things out properly. For me to type nonsense, I actually have to focus on the task.
So if your mind is a bunch of nonsense and it feels "NATURAL" for you '2 typ lik dis', then you need to ask your teacher about Resource classes.
My final thought is no, it isn't acceptable and should be stopped unless done in an acceptable situation.