"How can a reader trust a writer who seems to be ignorant of the medium she works in?"
My favorite part of the second chapter of Ursula K. Le Guin’s Steering the Craft is her “opinion piece” (i.e. rant) on “Grammatical Correctness.” Here’s just a bit of it:
I detest the self-righteous tones of those who sneer at other people’s speech, and I distrust their motives. But I have to walk a razor’s edge here in this book, because the fact is that “incorrect” usage, in written prose, unless part of a conscious, consistent dialect voice, is disastrous. It can invalidate a whole piece. How can a reader trust a writer who seems to be ignorant of the medium she works in?