I make mistakes typing. I’d take a bet you do too.
In fact, we all make mistakes when we write. It’s a fact of life. Everyone doesn’t have a proofer checking things behind them to make everything they write perfect.
So when you see a blog post (or a tweet, or a Facebook post or whatever) with a grammar mistake, don’t be an asshole and publicly post to the author “UR DOIN IT WRONG.”
That just makes the author feel bad and makes you look like an ass-hat.
Take the ten seconds it takes to send a private message to the author with the mistake. Chances are the author will fix it as soon as he or she can, and they won’t feel like they’ve been put in the stockades for a misplaced keystroke.
And then the internet will be nicer, if only for the briefest of moments.