According to "Let's Talk Hair":
1. Wet your hair thoroughly. Hold the hair midway between fingers of both hands and stretch the hair; if the hair tears or rips easily -- something is wrong! Strong healthy hair has an elastic nature and easily stretches and returns to it's original length.
2. If your hair mats and sticks together when it's wet -- something is wrong!
3. Is your hair thin, limp, and flat when wet and feels like straw and looks ashy when dry? If yes -- something is wrong!