Snitchin'

Within the Black community Snitchin is consider an ultimate low. Rapper Cam'ron was on 60 minutes when he stated that he wouldn't snitch on a serial killer. Why is it that snitchin is unaccpectable? We are always complaining about the crime infested neighborhoods, but yet when it comes down to help clean up the neighborhood and do our part by telling who's was involved we say nothing because we don't want to snitch. I don't get this and I need someone to explain to me why snitchin is so bad?