We all make spelling and grammar errors from time to time. Many are in the form of typos that we miss. Others are simply because we don't know how to spell certain words--whether it is a "e" or a "a", for instance. Still others are intentional, intended to bash or make fun out of an organization (the jokehovian witlesses) or god (joke-hova).
It isn't these types of errors that bother me. It is when people continually use shorthand spelling shortcuts, often making it difficult to read the post. This may be because you are texting from a mobile device and are paying by the character or that it takes so long to type each character that each one needs to count. If you are typing on a keyboard, it is not necessary to do this--especially if you are on a device where you are being charged a flat rate. I know it takes a little longer to type "to you" than "2 U". But, it is things like that that degrade posts and make people appear less intelligent than they are.
That said, I am also in favor of giving breaks for those who are not fluent in English. True, this forum dictates posting only in English. But, if people speak French, Italian, Russian, Spanish (a common one), German, or Chinese, their English is going to be weak. They are going to make grammar errors that would be correct in their native language. I would rather see them attempt to post in English and get it wrong than having them posting, say, in Spanish (or not at all). Especially those living where English is not their native language--it is asking a bit much for someone living in Mexico to learn proper English while they are in Spanish-speaking Mexico.