A couple guys from a group called Anti-Doping Research moseyed onto Amazon to see what they could find for sale. They've analyzed four of the supplements they bought so far, and surprise, "Three of the four tested so far have contained significant quantities of steroids."
To be fair, if your shopping list includes products called "P-Plex, X-Tren and M-Drol," (sample customer review: "P-Plex is a great Bulker. 10-15 lbs easy in a 4-5 week cycle. Make sure you have your PCT in check though. Slighty wet gains.") you know you're buying some fucking steroids.