First and foremost, the pizza should be Napoletana (or Salernitana).
What does that mean? It is not only authentic when coming from that area, but must look, taste, and feel like pizza from that area. I can tell if a pizza will be authentic by just looking at it. When my cousin from Salerno came to visit New York, I brought him to a New York Pizzeria. He took one shocked look at the pizza and said, “I am not eating.” He not only refused to eat the pizza, he refused to eat at all, being disgusted from the traumatizing experience. For Neapolitans, all it takes is a look.
The dough should not look like a hearty, unbendable loaf nor should it look like a cracker. It should not look bread-like nor should it be paper-thin. The pizza should not be hard as cardboard when you pick it up. Pizza should be bendable rather than foldable. The sauce should not be hidden under the cheese. Mozzarella di Bufala cheese is never to be plastered on in the amount of 3 inches. There should be only various spots of the water buffalo milk mozzarella, so the little sauce underneath is still visible.
As for the feel, the pizza should NOT crack on the bottom. Cracking means it is too dry and too thin. The dough should be cooked until it strikes the divine balance of being both mysteriously chewy and fluffy but still well cooked and NOT under cooked. The all-important crust (Il Cornicione) must be both crisp and chewy. It should be puffy, bubbly, and semi-charred with a few random, toasted, brown spots. The pizza MUST be the right depth. What is it here in America that people demand "super thin"? If the pizza is too thin, than it cannot carry the stuff on top of it. In America we tend to overload toppings. The overload principle is stupid. Who needs 6 pounds of food on a slice? GROW UP! Naples and Salerno do it perfectly, so the well-structured and correctly cooked pizza upholds the toppings and does not let it fall on the plate like bad pizzas do. In Naples, the pizza is brought to your table whole and uncut. You use a fork and knife to cut it, then if desired, is folded and eaten by hand. As a side note, Italians were using forks 300 years before other Europeans. As for the taste, it should be divine. To know what that is like, you'll have to book a plane ticket.