In short, you find out by asking the locals.
Just recently, I discovered a site that makes this kind of sleuthing even easier.
"Where the Locals Eat" lists the 100 best restaurants in the country's 50 largest cities. These won't necessarily be the newest or trendiest places. Instead, expect ethnic finds, comfort food standbys, and city favorites.
I particularly like the "Best Of" listings, which offer categories like the top French, Barbecue, or Brunch in town.
To make it even easier, the site has an iPhone application, so you can track down the spots while you're on the road.
Of course, there are other ways to get this information too.
Before most trips, I usually sneak an online peek at the city's magazine or newspapers. With just a bit of Googling, you can find the publication's annual "Best Of" list. My thought is that if a seafood dive or a pizza shop has been voted best in town, it's probably pretty good.
But it's hard to beat the convenience of checking just one site.
Do you agree with recommendations from "Where the Locals Eat" for your town?
Let us know in the comments below.