This article from the Los Angeles Times is worth a read:
Several months after supplements were recalled for being illegally laced with prescription drugs, researchers bought them off the shelves and from the online inventories of supplement retailers and checked whether they continued to contain the illegal substances for which they'd been recalled.In two-thirds of cases, the supplements did.
Link here: http://www.latimes.com/science/sciencenow/la-sci-supplements-fda-recall-20141021-story.html
