The term naughty is coined by parents who don't understand their kids behavior and the reasons behind it. Content babies are babies who are having their needs met emotionally and physically.
people just assume that babies cry because they are babies and kids are or can be "naughty" especially in relation to certain ages. (terrible 2s etc) but in actual fact. parents need to assume responsibility for their kids and provide them with the developmental and emotional surroundings appropriate to their individual kids rather then assuming that it is normal.