Reservoir Dogs: Mr. Orange - Plant or Just REALLY Bad Luck?

Okay, so I finally got around to watching Reservoir Dogs (I know, I'm late to the party!). It definitely lived up to the hype in terms of tension. The whole thing is just so claustrophobic and the paranoia is palpable. But the real question swirling in my brain is: Was Mr. Orange (Tim Roth) a plant from the get-go, or did everything just spectacularly fall apart around a guy who maybe wasn't cut out for the job? I mean, the whole 'fake story' rehearsal scene is telling, right? Joe Cabot clearly sees something in him to trust him with this vital mission. But then, Orange seems to screw up so badly early on, it's almost laughable. Did he mean to get shot? Was it a slip-up that he then had to capitalize on? Or, even crazier, did the cops KNOW about the job before Orange was brought in and just used him as a way to get close to Joe and capture all the dogs at once? I lean toward him not being a plant initially, if only because it feels more tragic that way. He's a rookie, in way over his head, and the pressure cooks his brain. The flashbacks slowly reveal how he starts losing his grip as he feels the weight of lying so much, on top of the trauma of the robbery going to hell. But the ambiguity is what makes it so great, I think. What do YOU guys think? Plant, incredibly unfortunate newbie, or something else entirely? I'm dying to hear your theories!