Though, thinking more about it, stealing queens seems... unlikely. It takes a lot of work to find a queen! Even if she's marked you still have to open the hive and pull out and examine some number of frames. If it's a big hive (say, "two deeps" and several "supers", that could be fifteen minutes if you're very good at it, or an hour if you're not. And you'd be very vulnerable to getting caught while doing it. If the queen is not marked then it takes that much more skill to find her, and you might have to look at every frame. So queen theft gangs seem unlikely to me.