I like to point this part out in particular: Reverse stings often involve small amounts of drugs being sold to individuals for personal use. These people are then either recruited as informants, or they are arrested and sent to jail. It is also fun to read about human intelligence in general. Most of what police do is human intelligence work. There is a nicer summary of why people become informants than the one used in this article, CIA breaks it down into four categories: MICE Money Ideaology Compromise Ego