He's fairly fatalistic in the novels, but doesn't emo as hard. And yeah, the biggest selling point to his character is his wits, the whole "Oh hey, a girl is jumping my cock and the other two girls who were doing the same act pissed, I wonder what could be the problem" part was fucking ridiculous.>>10046256
Saito is passably lecherous doing everyday life, which is one of the two reasons Louise doubts his feelings for her, the other being the familiar seal (Despite the fact that he's openly and clearly told her he loves her to her face a hundred times). He's chronically distracted by girls with giant racks and even goes as far as to nickname Tiffania "Bust Revolution" because he's never seen a girl with breasts so big.
On the other hand, he's got all his wits intact when it matters. He's very tactful when he refuses Siesta's attempt to sleep with him, realizes Henrietta is just jumping him on the rebound when she does the same and lets her down just as gently, and definitely doesn't start talking about chicks in critical or emotional situations.