Quality tomatoes are heavy for their size, firm but yielding, with skins that are intact and blemish-free. They have a distinct smell, especially at the stem end, that can only be described as "tomato-y." Tomatoes with no aroma have likely been refrigerated (not a good thing, as we'll see).
A tomato's color and shape should be characteristic of its variety. Color, of course, is a sign of ripeness. An odd shape often indicates that a tomato was literally nipped in the bud by cold weather, which damages its taste and texture. Color and shape together identify the tomato type, such as beefsteak, which in turn tells you whether a tomato is more sweet or acid, more "meaty" or juicy.
Once you find a worthy tomato, how do you keep it that way? Read on to find out.