my personal method when out and about is "ask a stranger," with using my hand computer as a backup. i delight in answering these questions as well, so i'm inclined to believe people generally don't mind.
What I've noticed is if you ask a random stranger what the 'best' is, you get the same generic, expensive fusion something made into a paste cuisine. If you ask their favorite, you find small, off-the-wall places with terrible selection, but amazing food.