Cricket, I know where you're coming from. I have the same tendency myself. I've been having discussions with someone at work about these assumptions, because I make snarky comments and laugh at silly mistakes that make the meaning entirely different from the intent. Working at a newspaper means that a great deal of my day goes into that endeavor! Anyway, I believe that Chris hit the nail on the head in saying that it indicates a lack of reading. For the same reason that I know how to spell a lot of words that I have no idea how to pronounce, many people know how to pronounce a lot of words that they have no idea how to spell; it comes down to whether you hear them or read them, and in both cases whether you hear or read them from an intelligent source. I still think it has something to do with education as well, in being able to discern whether what you are hearing or reading is correct. Yes, there is such a thing as a typo, but if it's consistent it's not a typo. Consistent misspellings or incorrect grammar are either lack of knowing or lack of caring.
We used to have a furniture store in town that had the word "furniture" misspelled three different ways on three different signs outside their store. I think that is an indication of sloppy business. If they can't be bothered to make sure their signs are correct in such a basic way, what else are they sloppy about? And if (undoubtedly) someone has told them it's wrong and they don't care enough to fix it, that's even worse. Yes, I'm judgmental.
On the other hand, does any of this mean that a person posting something basically illiterate does not truly have a gifted child? Not necessarily. I think that is something that might be determined over time, from the content of the discussion taken as a whole. But basically I think we (and when I say we, I mean mostly the lovely people who have been here far longer than I have and who take everything in stride) tend to just look at the surface and treat each post as if it were true, and over time I would suspect that anyone who "doesn't belong" fades off into the sunset.
So yes, I do notice and wonder about the (rare) illiterate posts sometimes, and yes, I probably should stop that, too. To paraphrase my co-worker, there are people we all know who can do fabulous things that we could never dream of doing and still can't spell cat without a dictionary, so it's all in what's important to you. Probably to my detriment, literacy is what's important to me.
