Cowan's rules range from the predictable (No. 5: "Admit what you don't know") to the puzzling (No. 1: "In the fanciest restaurants, order what sounds least appetizing"). The one my editor had in mind was actually an exception to No. 6 ("Prefer Vietnamese to Thai"), the exception being to try Thai restaurants that are attached to motels.
"Think of Victory Suites and Siam Square on Washtenaw," my editor reminded me.
Cowan favors Vietnamese food over Thai because it's less popular and so, he says, less likely to be watered down to appeal to Western tastes. But he figures that the Thai restaurants linked to motels probably are owned by a single Thai family, who are using the restaurant as a secondary income stream--and a place to eat dinner. The owners are free, then, to cook authentic, perhaps challenging but more delicious, food. Why else, in the U.S., would there be a Thai restaurant hooked to a motel, when a tired but predictable diner would be a safer bet?