Think about the people you know in your city. How could a visitor know which ones to ask for restaurant recommendations? It's almost impossible. But your odds are probably better if you ask people in the food industry, such as butchers or waiters (e.g., if you like a waiter in one restaurant, you might ask them to suggest other restaurants). And it doesn't hurt to ask anyone; often you can assess their judgment by listening to how they talk about the places they recommend. The same goes for reading crowdsourced reviews, of course.