Well there you go. BFF's. : P
I imagine most of the time, after the initial emotional backlash, that my opposite would actually have sympathy for your opposites emotional outbursts. (If anything, it might feed her need for drama.) She's not in the habit of remembering slights or holding others accountable for their actions. Especially not her homegirl, Straightjacket. ^^
(I suppose jackets aren't the opposite of coats, but I don't think anything is.... >> )
I in general just have a hard time describing positive traits. Talking about myself would probably sound pretty horrendous too if it were me listing myself in the same "case study that tells a story" fashion.
My opposite definitely has weaknesses that carry strengths that foil my weaknesses, like for example her overabundance of a willingness to partying foils my general wallflower tendency and preferring to not go unless someone I know already is there, while her obsession with trends and Lisa Frank colors foils my sticking to black and white and my distaste for things that trend to the point of disliking my own interests when they become popular. My opposite also, while more emotionally unbalanced, didn't have to deal with mental illness by the same understanding.
I'm not negating your point at all, you're right, but to me it's a matter of pointing out that, from my perspective in this case anyway, the opposite of crap is still shit. 
Mhm. To see it that way, you have to consider all your own traits as being the positive and anything opposite as negative traits. I don't see it that way because we all have positive and negative. So some of your negatives would be your opposite's positive. I could never write out a list of traits my opposite would have as being all foul and undesirable traits. I would have to think too highly of myself to see it as someone I have to hate. I understand night and day are opposites, but I don't feel I have to choose one to represent good and the other evil.
The opposite of me would be some dead girl. She probably killed herself. Who knows. .
Anyway, it was such a pleasure to read some of these. A few of them bleed with so much obvious contempt for that which is unlike "you". And also with pride in being so obviously the better personality to have. :D hahahaha!
I've already two opposite selves so that's that, but if it was someone i definitely am not it'd probably be extremely empathic and suffer from crippling emotional spikes, probably sexually repressed and heartbroken from overattachement to anything who gives it attention. Probably in deep denial of its action. Would probably act out of impulsion and never think before acting. most likely insecure with fragile masculinity making it a macho and an anoying sexist.