Put on your editor's cap for a moment and see if you can find the typo in this sentence: “Healthy doses of pepper spray and adrenaline were among the on-hand accouterments wielded by the two dozen Norfolk officers that responded to the embarrassing scene on the National Mall — a fracas occurring far closer to the Capitol than was considered safe in the judgment of the respondents' commanding officers.”
The mistake, which any editor would be expected to catch, is “Norfolk.” Virginia police wouldn't respond to a D.C. call.
Let's try another: “Poring over the menu at Chez Pierre, it's clear that creations like opah crepe hors d'oeuvres, lobster bisque and wasabi risotto — Executive Chef Jonathan Johns' signature dishes created with the help of his wife Madeleine — were designed to delight the palate and supersede his penultimate culinary accomplishment.”
No matter how carefully you pored over this sentence, you might never catch that the writer called Johns a polygamist. Without a comma before “Madeleine,” the writer implied that her name is “restrictive information” necessary to identify which of Johns' multiple wives we were talking about.