My wife owns/operates a travel business, so I've been very fortunate to travel and fish extensively down south over the years...Bahamas, Cuba, Mexico (Carribean and Pacific), Turks & Caicos, Costa Rica, Guatemala, Panama, Belize, Argentina, Chile...even the Cook Islands in the South Pacific. For the most part, all of the guides/charters that I've dealt with have been dedicated, hard working and professional. Almost all of them take great pride in what they do, and in most of these countries it's a respected profession that many aspire to..
The best of the best have been in Belize...it's a former British colony so they speak perfect English, and the government licensing program ensures they are well versed in boating and knowledge of the fishery. In terms of fly fishing, most of them have also been excellent instructors. I had a buddy come out with me that had never fly fished in his life, and by the end of the day he could put fly on a dinner plate out 60ft. Guides in the Bahamas out islands are a close second.
The one exception was an offshore charter in Cabo San Lucas, Mexico. The Captain and mate literally got so drunk that our group of 4 ended up taking over the boat (40ft sport cruiser), did our own fishing (we caught several Striped Marlin and Mahi) and drove the boat back to the marina with the 2 of them passed out..