Kids are kids, they don't always listen to their parents even if they happen to be the president of the united states.
I don't think this kind of behaviour from his children should make him look bad at all. If anything it makes me think "Wow he's got a normal damn family". Though regardless of what family values you or Bush hold, kids don't always listen or care and stuff like this happens.
Also she's 23 years old, she'san adult and is in college. I think whatever decisions she ultimately makes shouldn't reflect on her father.
And this is coming from an very anti-bush person.