I don't think there's any history of police stings in this context. It's far more likely that you run into a guy that's using fake or outdated pictures than a cop.
The question becomes 'is it worth $250-300 wager (plus hotel) to see if the guy in the ad is legit, his pics are accurate, and can he perform as agreed."
It's an expensive wager for many clients and in my experience often and losing wager, which is why I am very reluctant to try out a guy with no reliable feedback. But I am not worried about a police sting.