Like, mega sane. Here's the evidence, in long drawn-out form.
Of course, we all know he's the voice of reason on the Bebop. He's not irresponsible, he's always practical about stuff, like whenever Spike is about to do something stupid. He's always there to say "Spike, that's stupid." But he also knows there's nothing he can do to stop Spike from doing stupid stuff. The only times he gets really angry are when someone takes his money or his food.
In the episode "Ganymede Elegy", that's the one where the bounty is his ex-girlfriend's boyfriend, he's got this pocket watch, and he tells her he decided when she left to wait until the watch stopped. She's like, "Time didn't stop, dumbass!" well not in those exact words and she was a lot nicer about it [than I would have been], but you get the idea. But he's cool about it. He doesn't begrudge her anything, and he doesn't hate her boyfriend. He thinks her boyfriend is stupid, but he's right. So, then, at the end, he convinces the boyfriend that it'll be better if he faces the consequences rather than run and risk his life and the girl's. And (ok ok, maybe you HAVE seen it, I'm getting to my point!) then at the very end, he takes the stopped pocketwatch and throws it away or something (I forget exactly). It's symbolic that he's totally moving on and isn't going to dwell on the past. See? Sanity!
In the episode "Black Dog Serenade" (have I mentioned that ep enough recently for ya?) he didn't even hold enough of a grudge to go after Udai Taxim (the guy he thought shot his arm off). His ex-partner Fad had to talk him into it. Then when he finds out that Fad is the one who shot him, he doesn't go all ballistic. Then, and I have mentioned this before, he shoots Fad because he thinks Fad is about to shoot him. Then, instead of kicking him, like I would, he's totally over any grudge he might have had and not only gives him a smoke but places Fad's favorite 6-shooter in his hand. Sanity says there's no point holding a grudge against a dead guy, but I still hold a grudge against a guy I know who is dead now (he killed himself, and I'm still sorta mad at him for it). Even though it's completely pointless and a total waste of my resources.
Completely unrelated tangent, but I'm 34 you know and my dad informed me that he was completely gray well before he was 40. I figure it's just a couple more years for me. That'll be cool.
From a conversation I'm having online:
my friend:[Spike] has too much baggage.
me: and that's another part of Jet's sanity. By the end of the series, his only baggage is Spike's death.
(edited for grammar)
There is one episode in which Jet is not at all sane. That would be episode 11 Toys in the Attic. Spell 'attic'. hehehehe! (it's about Jet being sane. Not me.) He's decided to play dice with Faye. This is decidedly out of character, but he's bored and plus he loses his shorts which is cool. Naked! Hehehehehe! Anyway, it's not a major event or anything. There are probably other times, too.
But when it really counts, Jet is perfectly rational. And he's not even trying. It just comes natural to him. I'm sane about a lot of stuff, but I dunno if I'd be sane about the guy who shot my arm off if some guy had shot my arm off (which no one has, thankfully). And I don't think I could be rational if my best friend decided to go off on a suicide mission.
Anyway, there's yet another reason Jet is awesome. I have to go to bed now. Really.