As I'm planning to leave for Rome tomorrow, I've been perusing Frommer's and I found a really great list of dining tips for Rome which in my many years of trips there is definitely true. Here, I'm shortening them a lot but you get the gist:
1) Don't eat at any restaurant where the menu is translated into five languages (or where the menu is simply photographs of dishes)
2) Avoid restaurants where the waiters are trying to hustle you in
3) Most restaurants located on the main piazzas are big-time tourist traps
4) Do as the Romans do and follow the locals or ask at your hotel
5) Never order priced by weight fish without knowing what the overall price will be.
6) If you're on a budget (or me with my $25 per diem) stick to one meal, hoping you got breakfast free at the hotel. I always make it lunch, since I usually can't stay up late enough for an Italian dinner, especially with the time difference
7) Double check your bill. Even locals get charged sometimes for things they've never ordered (or gotten).