One of the frequent mistakes made by parents is talking proudly about their wards' negative aspects. This usually reinforces the ward's thinking that it is OK to be like that.
For example, one mother may say "My son does not listen to his father at all. But he will never cross the line I draw. He obeys me all the time." The son then takes more advantage of the father in not heeding his words. He also takes advantage from the mother by having a good name - sometimes we never know whether the child is just abiding time as long as he needs mother's care.
Sometimes the statements are with other qualities. For example, "My son is clever in saving money when dealing with barber / flower deliverer, etc." In effect, the son uses some devious methods to trick or even cheat the others from their due. This is being encouraged and many times comes back to roost as a very negative character, which the parents rue after a few years.
Parents should have the wisdom of highlighting only the good points in public and chide the children in private when they take the wrong path. This is the best for the long run for the children.