I get asked this question a lot. Unfortunately, any discussion of the problem of drugs in Latin America is usually too long and complex of an issue for the time and situations I tend to be in when the question arises.
Rather than listen to a lecture on the topic, I suggest a more interesting way to find out what it is like.
Read: "Crossfire" by Author Jeannette Windle. She is the award winning author of the popular "Veiled Freedom" (a book on Afghanistan), but she wrote an earlier book touching this very theme.
The book is a fictional Christian adventure/romance. But since Jeannette was raised on the mission field and latter returned as a wife of a missionary and raised her family in the area where the drama of her book unfolds, the book is extremely realistic.
If you want to know the issues we missionaries deal with regarding drug trafficking and corruption, this book will give you a very good idea of the realities we face down here.