You can learn a lot from a city’s local residents — including where you should and should not go out to eat. Ask locals for the best spots. That’s your best bet. But if you notice that a restaurant looks particularly deserted, take the social cue. One of three things is likely: The restaurant just happens not to be busy, has food not worth writing home about, or serves food that’s genuinely unsafe. For all you know, the spot could be known for risking food poisoning. A restaurant filled with local diners is less likely to be known for spreading sickness.