What is the secret that perry knows about dick that causes him to lose respect for dick?

Perry's especially repulsed by Dick's interest in young girls.

he had "no respect for people who can't control themselves sexually," especially when the lack of control involved what he called "pervertiness"—"bothering kids,"queer stuff, rape. And he thought he made his views obvious to Dick; indeed, hadn't they almost had a fistfight when quite recently he had prevented Dick from raping a terrified young girl? (ch 3)