By far the most spot on answer.
Might seem a little too intuitive--but you'll have the feeling even before she starts showing any observable symptoms. By far the best feeling you'll ever have with a woman--but that's why it's so important to be able to walk at the first red flag (like apple mentioned, the first red flag will be a sob story early on). Or at least know what you're dealing with.
If things start feeling impossibly perfect with a girl early on, I just wait for it--and enjoy that drug-like euphoria with one foot already out the door.
Absoloutley.
My bpd ex told me she had been raped in the past actually before we were even dating, during one of the first times i met her.
I later found out that she tells almost everyone as soon as she meets them, i think theres a gameplan to it as she told me and one of my friends around the same time, my reaction (sympathy) green lit further research on me before i was selected as a good supply source, my friends reaction (weirded out/confused) meant she didn't waste time on him.
I also agree with what the other poster said about the eyes, i can't belive i never picked up on it before, i always liked her eyes but when i look at pictures now that i know, i see haunting, hypnotic but most importantly empty, dark eyes.
I think the saddest thing is that after it all goes down and you get educated on the disorder, you realise that you had basically been compensating for their missing personality (they really do not have a unique individual personality, just a script they follow with every new person they meet) with your own imagination, and when you hear from them now and again, it really is like they are on rails automotons, completely predictable and governed by their disorder, there's very little, if any, free-thought going on in there. It's unnerving.
I remember once toward the end i said to mine "i wish we could just have an open, honest conversation about things, and just discuss thingsand come up with a solution"
and she said "we can"
and i said "go on then"
and she just sat there, confused, almost crying, completley unable to rationally discuss things.
It really was tragic, i think she wanted to, but i'd just made her realise she couldn't do it.