I’m not a grammar Nazi. That’s being a bit harsh. I’m a grammar conservative with a slightly authoritarian bent, I’m a grammar pain in the butt, a grammar noodge. Not really a Nazi, though. I’m not likely to unfriend anybody just over grammar mistakes, unless they’re an asshole about it and I also disagree with their political opinions, and if those two things are true I might unfriend them anyway, even if their grammar and spelling are impeccable.
Also, I realized early in my internet experience that correcting every grammar or spelling error on Facebook would be a never ending and, ultimately, unpleasant task, and I generally avoid unpleasant tasks, especially those I’m not getting paid for.
So, I decided to become a specialist. I correct people whenever they spell lose with two o’s, and I correct people who write could of, would of, and should of.
Your v. you’re, or their v. they’re v. there might just be a typo, and I’ve slipped up occasionally myself. I might sometimes make a joking comment if somebody picks the wrong homonym. (yesterday I caught somebody writing ‘He was dressed in black from head to tow’ and I couldn’t just let that pass)
I think one reason for the spelling errors is that people don’t read enough, and it shows that they know the word from having heard it and not from having seen it in print. So, when somebody writes “You are a looser,” they are trying to transcribe “You are a loooooooser,” but they’re getting it wrong. And with ‘could of,’ etc…, that is pretty much what it sounds like.
It’s sort of a corollary to the Dunning-Krueger theory. People who don’t read, and therefore have bad grammar and spelling, don’t seem to be aware that people who DO read, and have large vocabularies which they use correctly, can spot them as non-readers in a second.
Or else they just don’t care, which is scarier.