The teacher's visible scars serve as a reminder of the pain and hurt that this world can inflict. All the characters are scarred in some way, either figuratively or literally, tainted by the ugliness of this world. It is the immersion into the underbelly of society that diminishes the enjoyment level of the film. Many of the scenes are emotionally wrenching, oftentimes to a unhappy resolution. Young Osment uses many of the mannerisms which worked so well for him in The Sixth Sense and they are just as effective, if a bit familiar, in this film as well.
Hunt struggles, working against type as a trashy, bleached blonde, undereducated alcoholic.
It is Spacey's performance as the physically and emotionally scarred teacher which resonates the loudest. The raw vulnerability of the character is almost embarrassing to watch and helps us to understand that everything else this character does is part of his defense mechanism. Part of the flaw of Pay It Forward is in the depiction of the good deeds themselves. Trevor's first act is an ill-advised one of bringing home a homeless drug addict and letting him spend the night. We should all aspire to do good for others, but we must be wise in our actions and true to the laws of the land.