Internally, Hickey's bristling at his words. But there's something about what Rorschach says that catches his attention. Billy has the brains. Billy can do better. This could be just Rorschach trying to get under his skin, using whatever words and whatever ammunition he has at his disposal. But why bring up Billy like that? There's plenty of other things he could use to attack Hickey.

So Hickey pushes down his ever growing anger (even though he really wants to stab that asshole and watch him bleed, it would benefit him to be the wounded party here) as he instead just points out,

"You keep mentioning Billy. Even if we weren't together, you'd never have a chance with him. Billy prefers people who bathe. Who keep clean. When's the last time you washed that mask of yours, hmm?"