I'm talking about the substances found one time only. There are no doctors who want give athletes some PED who can use strange substances for that goal, substances that no dirty doctors in the most evolved Countries give their athletes. The effect on the performances of those substances are very poor (or, better, don't exist), and the proof of this is the fact that more the doctors know illegal drugs able to give big advantages, more they use. This means that the variety of illegal substances used by one athlete only probably are not prescribed for improving training or performances, but probably are, in small qualtity, in some drug produced in Asia, where there is not the must to detail the components of the medicine.
In my opinion, athletes caught for Nandrolone, Corticosteroids, EPO wanted to dope for improving training and performances, while athletes caught for drugs normally not used for doping are positive because unlucky (substances in some medicine used for treating some sickness) or careless