Focus on Deficiencies
(1) Description of the pattern
This pattern suggests that the best way to look at a community (or other things presumably) is to focus on its deficiencies; what's broken or dysfunctional. Thus, one can "diagnose" a community for its "diseases" such as crime, drug use, broken families, or "loose morals."
(2) Why the pattern is good (i.e. bad)
This pattern is good because it reinforces the idea that the particular thing being looked at is bad fundamentally. This helps people in the community to feel that they're worthless and are incapable of doing anything positive. It also can justify the need for "professionals" to come in from outside and clean up everything. The pattern also helps disregard the things that are good about the community and represent potential "local" solutions. If these assets are ignored, then it's very easy to simply not think about supporting them.