Why, Dad?

My daughter started asking "why?" today, suddenly. She's starting with the hard questions.

1. "Why [aren't the white shoes good park shoes]?" Dumbfounded, the best I could come up with was "because there are holes in them". (They are sort of like sandal-shoes.) My answer was so unsatisfying (to both of us), I put on the white shoes.

2. I was washing my hands tonight, and she walks up to the bathroom and asks, "Why [are your] hands dirty?" I still don't know how to answer that question.