"If it does make sense to use some spyware, I would never do that in secret way," said Walsh, whose own three children are now adults. "Tell your children you'll check on them from time to time. Just that knowledge can be effective."
Parental dilemma: Whether to spy on their kids →
David Walsh directed an adolescent treatment program earlier in his career and says the at-home tests can be appropriate when parents have solid reason for suspicion.