Here's a hint: Everyone, to a point, is shallow. Men, women, high schoolers, middle schoolers.
Most men (and women) are shallow. They continue to be shallow for most of their lives, but the peak of said shallowness occurs in the adolescent years. High school and middle school students aren't looking for a "good" person to be with. After all, a teenage romance doesn't really go anywhere, does it? Why look for a compatible, "nice" person while you can have a temporary fling with a "hot" one?