As if the dopes taking this kind of stuff weren't wasting their money to begin with, most of it's not even what it's supposed to be:
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...Overall, [only] 21 percent of the test results from store brand herbal supplements contained DNA from the plants listed on the labels. The retailer with the poorest showing was Walmart, where 4 percent of the products tested showed DNA from the plants listed on the labels.
http://www.nbcnewyork.com/news/local/Eric-Schneiderman-Herbal-Supplements-New-York-Walmart-GNC-Walgreens-290640551.html