Isn't this sadly the truth - we so often take for granted when the people we love best do something good, but frequently lambast them when they do something bad. How on Earth is that supposed to encourage good behavior? (and is discouraging bad behavior really enough?)
I've been trying in my own relationships to practice this more over the past few years - I try to compliment the good things people do even if they seem natural given the circumstances. "What do you want, a medal" is still default, but that's just rewarding good behavior with sarcasm and ridicule. Not ideal. :)