Call me crazy, but I can't help but feel that any pimp who would otherwise traffic young women against their wills would not do so given the option to traffic a robot that doesn't have a will. For one thing the robot isn't going to require food or sleep or any of the other things those pesky humans need. At most it might need plugged in for a few hours every day. For another trafficked women sometimes escape and almost always want to, whereas the robot wouldn't. All in all pimping out a sexbot would be a whole lot less headache than pimping out a woman. Basically if the things were convincing enough (ie, more human-like than we can currently make them and firmly on the other side of the uncanny valley) and within a certain price range (cheaper than a human slave but much more expensive than a night with a prostitute) I could very easily see them making a bigger dent in the human trafficking problem than any thing else we could do.