re: Reports out that Clem players’ “B” sample also positive for PEDs.

While I don't doubt that some supplements can withhold ingredients from their label, it certainly is not going to be any of the "major" brands. There are "blacklisted" brands enumerated on anti-doping agency websites that professional/premiere collegiate athletes should be aware of.

On top of this, Clemon's athletic staff mentioned they are in "control" of what supplements athletes use. Well, if this was the case, you would think a fair amount of research, testing, and verification would be part of the selection process on top of using trusted brands that are 3rd party approved for their ingredient list.

In the end, even if I did believe it was entirely incidental, a high caliber athlete is solely responsible for what they consume and should perform the due process as above. And, to answer your question, athletes evade drug tests more often than they are confirmed positive. I have no doubt that most collegiate/professional athletes are using PEDs.