When the person promoting the product is putting on “the grimace,” the market has a field day. In case you’ve been napping, McDonald’s launched its new Big Arch burger in the United States this week. Two all-beef quarter-pound patties. Three slices of white cheddar. Lettuce, pickles, two types of onions, and a new tangy “Big Arch Sauce,” all on a sesame-poppy seed bun. It’s a lot to take in. Literally. At around 1,020 calories and roughly 8–9 bucks for the burger, it was positioned as the...