Quote 4
His sexuality was anything but lewd; his patronage of little girls smacked of innocence and was associated in his mind with cleanliness. He was what one might call a very clean old man. (3.9.5)
Soaphead's rationalization of his behavior should be taken with a huge grain of salt here. In any case, the passage shows how his sexual attraction to young girls correlates directly with his attempt to purify himself, both racially and spiritually. It also seems to be a way to combat his first wife Velma's rejection. "Clean old man" is a funny twist on the phrase "dirty old man."
Quote 5
His sexuality was anything but lewd; his patronage of little girls smacked of innocence and was associated in his mind with cleanliness. He was what one might call a very clean old man. (3.9.5)
Soaphead – the sole academic figure in the book – uses his intelligence to manipulate the concept of innocence, extending it to include his own sexuality.