Okay so I respond. I say I'm your mole. FBI agents show up at my door the next day.

Sure, you could run a simple sting operation against foolish sorts who declare "Mole in training. Looking for companies to bust". But there are a lot more sophisticated ways of thinking about putting sources in place than something as brute force as that. Without being too helpful to miscreants, it doesn't take much thought to come up with far better Craigslist-based approaches that would be much more difficult to prevent.