First of all, unless it's a really good hotel, a good boutique hotel, or some small family run place, I would never ask the hotel staff. If the hotel insists on doing a booking or gives you some piece of paper to give to the restaurant (or if you notice the taxi driver going into the restaurant when patrons are dropped off), this means that there's a well established kickback system, so run in the opposite direction. It's even worse if the hotel "concierge" offers to arrange a "free" ride to the restaurant. For fine dining restaurants, the AmEx fine dining restaurants would be a starting point in places not covered by Michelin or Gault Millault. (Ignore AAA book listings for restaurants unless you just want a handy list of a few addresses and phone numbers.) I often do well just walking around and observing restaurants, including any posted menus. Some people swear by the theory that if you see a line, it must be good, but this can just mean that it's cheap or is a well known tourist trap and I don't like waiting for a table.

For a real local place, one rule would be to ask in some unrelated shop that seems to have locals, for instance ask about a local Chinese restaurant in the neighborhood by approaching the person who works in the newsstand.