I rescued Rosie, a tortoiseshell/white cat, from an Animal Sanctuary 5 years ago when she was 2. They'd had her for 8 months and no-one would take her on because she bit. I was told she bit because she'd been cruelly treated in the past.
I fell in love with her straight away and, as I've had cats all my life, thought 'she won't bite me'. Well, pride comes before a fall and yes, of course she bit me, right through to the bone, and I still have the scar on my hand to prove it!!
She settled down eventually, though, put the past behind her and became a friendly and affectionate pet. I wouldn't be without her.