At the Macmillan Dictionary blog, the ever-thoughtful Stan Carey has a post on fault-finding in language, in which he explains how the impulse to correct errors may "target the wrong people."
"Criticising language use is a political act," he writes, and "malice or petty triumphalism is often what motivates people to highlight errors." That danger, you may recall, is why I advised the other day against employing [sic], because it's almost impossible to do so without displaying a snotty superiority.
Copy editors, of course, are professional fault-finders. I've used the medical analogy that we are surgeons, curing with the knife, but it's perhaps more apposite to say that we are like pathologists. We haven't been engaged to focus on healthy tissue.
That tendency to focus on identifying and correcting errors can, regrettably, lead to dog whistle editing or excessive zeal.
Now it can be told: Back in the day, when The Sun was still regularly hiring copy editors,* my brutal applicant test contained a short article that had nothing much the matter with it. Any applicant who went to town on it, penciling in multiple corrections or recasting sentences, was automatically disqualified, because such an editor would (a) take forever to get anything done and (b) bring down on my head a storm of complaints from writers about edits that could not be justified.
That fault-finding tendency has to be kept in check, lest it lead to excess. You'll remember the two gits who went on a campaign around the country to correct errors in public signage and wound up fined by a federal judge for defacing an historic sign in a national park. (No, I'm not going to identify them and give grammar vigilante bozos further publicity. Being an English major does not license you to be a prig.)
Really, if your self-esteem is so frail that it must be bolstered by correcting grocer's apostrophes, you ought not to disport yourself in public.
*We were repeatedly interviewing and testing because as soon as my hires displayed their mettle, they were promoted off the desk or plucked from the paper altogether by parties like The New York Expletive Times.