How to spot good parenting?

A kid behaving well or badly can be due to a lot of reasons. A seemingly well-behaved kid is obedient because his parents use harsh, punitive punishment when he misbehaves. He can also behave well because he sees his bad parents as the don't-do "role model". So I don't believe in judging good parenting by the child's behavior.
But you can judge by the parents' behavior -- are they doing the right thing? How much effort have they put into it. Of course, there can still be time when parents do all the "right things" but the child still doesn't turn out well. Good parenting cannot guarantee outcome. Good parenting is about doing the absolutely best the parent can and make no excuses.