Scott H. Decker and Margaret Townsend’s"Drug Smugglers on Drug Smuggling" is an interesting read on that particular form of crime, written as an auxiliary text for criminology students, so not exactly leisure reading…
Bottom line – Nearly all drug smuggling busts arise from a trusted ally turning them in. Either by foolishly getting caught himself and turning state’s evidence, or as a plant. Drug smugglers do not fear the Coast Guard, which is impotent if they don’t have a tipoff, but they fear Bahamian’s who are out looking for smugglers to hijack, and are not constrained by constitutional niceties.
This point is made exactly, and more dramatically (no offense Noel Prosequi) in a great scene by Mickey Rourke, a former bomber who advises his former defense attorney on what’s what.
There also a pair of American thieves who had a remarkable run and were only caught in their later years from a happenstance traffic stop where the policeman found thousands of keys and burglary tools in their trunk. There was actually a TV true crime documentary about their careers but I can’t remember their names for the life of me.