4) An overly lenient testing system. F.ex. giving warning calls and accepting excuses. See USADA and AKAD, at least until 2020/2017.
5) A corrupt testing system. F.ex. testers or labs accepting bribes. See IAAF back then. Possibly AKAD now.
6) An enabling "testing" system. F. ex. RUSADA back then.
Finally, it should be common knowledge by now that the really sophisticated doping can only be caught with whistleblowers.




