Some years ago, my Industrial Law lecturer was telling the class about the standard he expected to see in our assignments. It was to be of the same standard as a barrister's letter of advice, he said. "Spelling and grammar perfect," he said, and went on to the more technical aspects.
Something about the matter-of-course way he just tossed this off caught my attention, because it was something I had not heard for a long time. There were mutters about the class, but it seemed right to me. Law isn't for babies. When you've signed contracts on your dream home and someone gazumps you, when your employer refuses to pay your statutory superannuation, when your spouse leaves you and denies you access to your children, you are going to want a fully-functioning adult human being representing you. It's what you pay for, and what you expect.
If we casually take for granted that a lawyer will have a complete mastery of his language, why would we not expect the same thing as a bare minimum from an author? After all, writing is all we do. It's not some frilly add-on; it's not mere presentation, with the main job being our knowledge of the law, as it is with a barrister. It is the one thing for which we exist. If we are going to publish a book and take people's money for it, have those people not a right to expect that we be competent in our language? It seems to me that to fail to meet this basic expectation is fundamentally dishonest. It's like a cleaner who just sprays some Mr Sheen about your house and expects to be paid for two hours' work, or a mechanic who takes out a part, sprays it black, puts it back in and charges you for a replacement.
And that is why, when I review a book, my basic expectation is as that of my long-ago lecturer. Spelling and Grammar perfect. Anything less is cheating the reader.