10 grammar mistakes that make you look like an idiot

Allow me to reiterate, o erudite ones. As a native born Northumbrian I say could of as part of my oral vernacular culture, of which I am rightfully proud. It is not a grammatical mistake, more of a pragmatic anomaly, though of course this will be lost on small-minded pedants hung up The Rule. The Rule derives from what it has observed to be the consensus, as such it remains, in essence, a theoretical construct. The Rule does not define the nature of that consensus, much less contain it; nor does it allow for the fact that there will always be exceptions, not so much to prove it, but to give the lie to the very notion that something as vital, rich and eternally diverse as the English Language can ever be understood in such simplistically puerile terms of right and wrong.   

I must say Don, I'm deeply disappointed by your handling of this matter, not to mention resentful for having some American calling me an idiot for speaking the way I do.