Nonito Donaire underwent year round tests. Luis Ortiz is doing the same. (because he already got busted once for something) WBC has their top contenders undergo year round testing. There will always be some who are clean.
Have any credible data to validate that? How about personal experience? Probably neither....move along then.
https://twitter.com/lucasBrowne And his Twitter is gone. Probably realized he won't get off the hook the 2nd time.