In the counterespionage world, double agents (DAs) are individuals who pretend to be spies working on behalf of your adversary, but in reality, they are doubled back and actually working for you. They serve many purposes, not the least of which is to channel disinformation out to your adversary for a variety of purposes (to blunt their intelligence efforts, misdirect resources, create confusion, or to manage perceptions, for example).
The most common method for inserting DAs is the simple dangle operation. Like a shiny object, an individual approaching a hostile intelligence service purporting to have access to valuable intelligence is likely to be recruited and enter the graces of your adversary. Once recruited, you now have a conduit through which you can engage in mayhem (it can be quite fun, by the way).
One nice thing about DA ops is the practitioners who develop them spend years training and honing their skills. After all, a good intelligence officer is likely to spot an obvious dangle and refuse to chase the bait. As a seasoned counterintelligence operative, I spent many years in the heady Cold War era working DA ops. I used a variety of tradecraft to not only mask the true intentions of our DA ops, but to spot the efforts by the KGB to insert spies in our camp.
In ideal ops, DAs receive extensive tradecraft training, but if they are not up to par, their efforts become humorous at times. Dangles can be easy to spot, especially if it is a clumsy and unsophisticated operation. Now, not all is wasted with a lousy op. Once we spot an agent provocateur, we will exploit that DA to pass our own disinformation back to the hostile service. That’s the price to be paid in the espionage game for not having your act together.