Being fun and active is not exclusive to dumb girls. This is an actual problem, when people seems to have the conception that being happy, girly, feminine are signs of weakness or smaller mind. That used to be one of the running horse of feminism, that these traits arent weakness and many women with some of these trait or all of them are just as smart as someone else. Now of course feminism is different now and doesent really care about inclusion, but it does not matter.
Ill let real experience speak for itself. I go to the gym with a coworker that is as close to ditzy as i can think off, the kind that start dancing on the walkway to music, the kind that changes nail polish every other day. She still have a bachelor in health science and talking to her is pretty nice because shes cultivated.