I had a conversation with my sister today about "mean people". She had a very bad experience at Costco today and was in the mindset of "people are bad". I know lots of people who agree with this position, which is the dictionary definition of cynicism.
I tend to be on the other side. It's not that I don't agree that "mean people" exist, it's just that I am more inclined to see the reasons behing their meanness, to the point where I will make up such reasons despite having no evidence to show for them. Some call this naivete, but I'm well aware that I am probably wrong often.
In the end, though, from a Christian perspective it doesn't matter! Our actions towards others should still be the same, whether we think they are good or bad. We are to bless those who curse us, love our enemies and welcome hardship and persecution. Easier said than done, no doubt. But the whole discussion about people being "good" or "bad" takes on an entirely irrelevant tone in the light of Jesus' attitude towards everyone. He certainly had cause to decide that people were bad, since compared to Him they most definitely are. But he chose to love them anyhow. Even those who nailed him to the cross he asked that the Father forgive, for they didn't know what they were doing. Ironically, someone who tends to be more optimistic about people may fall into condemning "bad" people far worse than the cynics, simply because we eroneously belive that they are somehow an exception.
I know for a fact how flawed and sinful I am, yet Jesus forgives and loves me, and it is all I can do to remember that everytime someone cuts me off in traffic or yells at me when I don't deserve it.