Now that the dust—and mouse droppings and improperly-handled meat—has settled, how have the New York City Department of Health's letter grades for restaurants affected business since they became public in July? Well, for the 15 percent who scored the lowest "C" grade, it hasn't been great—many diners are avoiding them, even if they were previously regulars. 

And there have been a few high-profile surprises as well: Thomas Keller's celebrated Per Se had enough violations to keep him off his "A" game during the first round of inspections. (His official grade won't be established until Keller has a chance to address the violations and the restaurant is re-inspected.)

According to our culinary brethren in Los Angeles—who have been subject to letter grades for over a decade—the system definitely has a monetary impact. "If you go from an A to B, you lose revenue," says Dr. Jonathan Fielding, director of the L.A. Department of Public Health, who oversaw the implementation of the grading system in 1998. On a positive note, it's been great for diners, as more restaurants have cleaned up their acts: 83.3 percent of restaurants in La La Land earn an "A" today, as opposed to 63 percent in 1998.

In the meantime, Jean-Georges Vongerichten—whose eponymous restaurant was visited by a cockroach earlier this year—welcomes the scrutiny. "At one of my restaurants, they came at 9 in the morning and there was nothing in the fridge, nothing on the stove—and we got an A right away," he told me at a James Beard Foundation event in New York City recently. "At another restaurant they came in at 8 at night, in the middle of the rush, so getting an A is not as easy. We do everything we can and we spend a lot of money [to get an A]. And I think it's a good thing. No one wants to eat from a dirty kitchen."