Because I love dirty girls, and any girl that loves me cumming on her face is very dirty. My girlfriend lets me cum anywhere on her, I just tend to keep it in her holes. Still, a huge turn on knowing I have free rein.
Clean girls, dirty girls. It doesn't matter to me. As long as I can cum on them I am happy. It's better with good girls, as you can dirty them with your seed. Ooohhh yeh.