Right on, Kat. I've been teaching English composition (i.e., writing) on the college level since 1974. On the whole, non-native speakers of English tend to do better because they come with the "rules" of grammar, usage, and composition already in place.
However, please note that no clear set of standards exist except in the context of actual use. Thus, I will not complain about the lack of apostrophes, comma splices, run-ons, etc. in some of the posts above because the standards, such as they are, are different in this context than they would be in, say, an article written for formal publication in an academic journal.
Beyond that, any serious student of the language will tell you that it changes. People in my field are mostly "descriptive" rather than "proscriptive" grammarians. As one of my own teachers once commented, "God did not lower the rules of English grammar down from heaven on a string."
For example, the apostrophe is slowly disappearing from the language. It is being replaced by the so-called "genitive by juxtaposition." These days, no self-respecting steak-house owner would call his place Smith's Steakhouse." It's the Smith Steakhouse. And come to think of it, when did steakhouse become one word instead of two? In fact, I'll bet you all a nickel that "would of" will be an acceptable replacement for "would have" in 50 years or so just as 'have not got" became an acceptable replacement in informal speech for "have not gotten" in England a few decades back.
Language changes, and be glad it has. English nouns used to have declinations just like Latin ones. How would you like to have to add endings to all your nouns depending on their grammatical position in a sentence? I'm perfectly happy with saying "you" in most cases except the possessive instead of having to figure out all the permutations of "thee, thine, and thou." I just wish the culture at large would accept the southern use of "ya'll." English needs a second-person plural form of the pronoun.
When I fall down while hiking, I cuss. I do not curse or swear or use foul language. I cuss, dag nabbit. And don't ya'll fergit it. :-)