Psychological problems in kids are roughly divided into externalizing behaviors and internalizing behavior. The former is basically acting out: doing poorly in school, being hyperactive, being oppositional, getting into fights, throwing tantrums and the like.
As I have often joked, when it comes to looking at the home environment, most mental health professions will - if they say anything at all - label it as "within normal limits (WNL)." What WNL usually really means is "We never looked." If they do "look," they may ask the parents one or two questions about discipline, and take their answers at face value as well as valid or complete.