Awesome point.
Just curious.
How does someone know the difference. For sure?
I mean as we ALL know these ladies can be very deceptive.
You're right, it's not like we can always be 100% sure, especially if it's a first visit. If we've seen her before, and she was more into it on previous visits, then yeah, she's probably just not into it today. Or if someone else has given her a rave review based on her performance, but she won't even look me in the eye, then maybe she's just not into me. But if it's my first visit and she's making no eye contact, no effort to interact, staring blankly at the ceiling, then the odds tilt sharply to her being a trafficking victim. The ladies are indeed deceptive, but if they're there of their own free will, they have a huge monetary incentive to get us engaged in the session so that we'll come back. Something is pretty clearly wrong when the provider acts like the one described by the OP.
Even if we're not sure whether it's trafficking or simply lack of interest, I'd rather err on the side of cutting the girl some slack.
Take care, guy.