Children need love, especially when they do not deserve it. ~Harold Hulbert
It's easy to love the 'good' child, but it's the 'not so good' child that really needs to know he's loved. Adults, myself included, are naturally drawn to the 'good' children and treat them differently, often making them our favorites. Sometimes all a child needs is to know they are loved and they will change their behavior. Not to mention the positive effects on their social/emotional development!
I've had my share of ill-behaved children in my classes over the years. I've been able to win over a few with this philosophy. Even in the ones I didn't win over, I hope I at least made a difference.