(i apologize for how long this post got but i think it's all relevant info)
few months ago my SIL stumbled upon a cat coming out of the subway. the cat followed her home and, predictably, they took her in. had her spayed, got all the shots done but she was terrorizing one of their cats so they made a decision to adopt her out. two women came to adopt her but returned her a week later complaining that she was biting them.
we thought they just happened to be inexperienced cat owners. in order to avoid more feline stress in my brother's household, they brought her to my mother's house so that we could try and find her a home. she initially fought a little with our cats (she mostly terrorized the two youngsters, didn't bother with my 17 year old male at all) but somehow everyone survived and all seemed well. however, few days later, she jumped up on my mom's leg in what my mom perceived to be an attempt to bite her. still in disbelief, my mom dismissed it as just a misunderstanding. few days later, we were scheduled to take her to a local pet store for adoption day. my mom went to pick her up and the cat went crazy on her. my mom promptly gave up. she's calling our regular small animal vet today to discuss this with him.
she's otherwise v. social, loves to spend time with humans, follows us from room to room, rubs herself on our legs, acts v. friendly. i can pet her without any issues around her head and neck. my mom says that she got aggressive when she tried to touch her tail but i don't find that unusual with a cat (male or female). one more thing is that although she uses the litter box just fine, she also pees (marks?) throughout portions of the house. not sure if this is related to the other issue.
my mom is moving overseas so she can't stay there. it's kind of hard to put up for adoption a cat that seems to have some potentially significant aggression issues. i'd hate for some unsuspecting soul to take her and then when she bites them, to dump her.
An online search on cat aggression brings up several good academic sites including one from Cornell U. Found good info online when dealing with a cat at our house who was claiming our bed for her own and couldn't be picked up.
Sorry you're dealing with this - it can be a very bizarre journey figuring out what's going on, and you're right that you can't easily adopt her out to anybody but a person who enjoys the challenge of rehabbing difficult animals.
We used ideas from what I found online, bolstered with courage that I gained from using our big leather fireplace gloves whenever I had to pick her up and declare my space. It's strangely like dealing with horses, establishing yourself as the alpha and making THEM move.