Well, now that this has turned into a discussion about grammar in general, spoken grammar mistakes don't bother me anywhere near as much. It's just the inherent different between descriptive and prescriptive grammar. (For those that don't know, descriptive grammar is essentially the "grammar" of everyday speech, warts and all, and prescriptive grammar is the hard and fast rules. I'm oversimplifying a lot, but that's basically it.) I'm in school as a partial linguist so I hardly even notice spoken mistakes anymore since they're just a part of life and are honestly kind of interesting because a lot of grammar inconsistencies are regional/cultural, even for people who might know better. I'll be the first to admit every once in a while I'll say "me and so-and-so" instead of "so-and-so and I/me" despite the fact I know the latter is correct. I just generally feel that in this day and age, especially with spellcheckers, people should take the time to review what they have written... whether it be on a forum, website, letter to a friend-- anything. Of course no one is discounting or being judgmental of certain circumstances that make spelling and/or grammar a challenge such as dyslexia or true lack of knowledge, and there are certainly people in the US and all over the world who did not even receive an adequate or any elementary education
through no fault of their own. My overarching feeling is the people that SHOULD know and probably do know what is correct should ensure to the best of their ability that their written words are true to the English language... because most people who should and do know would then make almost no mistakes.
Confession: when I was typing quickly, the first thing I typed was "because most people who should and do know would them make almost know mistakes."
