^While I agree that obtaining drugs illegally carries with it the risk of purchasing counterfeit or otherwise non-active drugs, but typically, pills and branded pharmaceuticals can be trusted. Now, when you're dealing with pills that are immensely popular with a huge market i.e. "Perc 30's"; "OC 80's: (Oxycodone), then yes, you are more likely to encounter counterfeit material.
But, when you're dealing with the cornucopia of different brands and presses, it's unlikely that these amateurs distributing the counterfeit have a die for every single pill out there. So, in general, you can trust pharmaceuticals and significantly moreso than powdered drugs.