I bump into a friend who I've not met in years, mainly because for the interluding years, she was attached to a complete good-for-nothing, abusive slob of a human. She immediately latches on to me, tells me how much she's missed me, hugs me, holds my hand, dances with me and all the rest. Now I'll be honest, yeah, I've had a bit of a thing for her. For, like, years. But what I didn't realize was that during the course of the night, she'd been doing exactly the same thing to a load of other people, many of whom I would consier my good friends.
I was absolutely furious. So the one thing she wants to do after being in a relationship with such a feeble excuse for a form of life, is to go whore herself out to whoever else she can find who she thinks still cares about her? Yet again, I'd been led on for no good reason without even suspecting a thing.
So why am I writing this? Basically I'd like to know from anyone so kind as to let me know - how do I avoid such a thing happening in future? Is there any way to tell if someone is just leading me on? The same thing has happened to me on many occasions before, and I'm never able to tell the difference between that, and if somebody is actually genuinely interested in me

In all honesty, I don't really know for sure if indeed what she did was with intention of hooking up with someone else. Unless she sleept with you or made it obvious that she wants to be with you or anyone else at the time of this incident then I think really it was just "i really missed you high school bud" sitiation. Anyway I think you're just misintreperting her like many other aspies.