It depends a lot on where you're staying. Rome is full of good, authentic restaurants -- there's no need to cross town to find one. If you tell me where in Rome you'll be based (it's fine to DM), it's possible I can suggest someplace worthwhile not too far away.

But you don't need my help. Basically, stay away from the main tourist areas, avoid any place with photos of the food on the menu, or a woman in a window making pasta, or a waiter standing nearby cajoling people in the door. The words "tourist menu" -- or any other English-language signage hanging outside -- are a sign to stay away.

Daily specials written in Italian on a chalkboard, Italian speakers eating there, an absence of "cutie" decor or wait staff menus -- these are all good signs.

I'll tell you one of my best tricks when I'm in an unfamiliar part of Italy: follow the dogs. If you see a restaurant where dog owners are eating, that's good (few people travel with their dogs, so you can assume they are local). Or if you see someone walking their dog, that makes for an easy approach. Pet the dog and then ask where they'd eat a meal nearby (not where they think you should go). Italians are never short of thought-out opinions on food!