@Dextro .45 - Obviously I know almost nothing of which you speak. I just wondered why specifically testosterone? I can remember when the BALCO scandal happened. Obviously I was more interested in the chemistry and what the chemist at BALCO had worked were three things:
1-Tetrahydrogestinone is (or at least was) considered the most potent and most active anabolic steroid.
2-Gestrinone was available as an API and finds clinical use in the treatment of endometriosis.
3-Gestrinone could be reduced to tetrahydrogestinone in one quantitative yielding step needing nothing more than palladium on carbon (catalyst), methanol (solvent) and hydrogen.
I was at once appalled & intrigued then after some research, impressed. Impressed that someone had simply looked at what steroids were legally available and what (if anything) a small modification would make.
Even decades later, the Turkish Olympic weighlifting team were banned for using RU-2309, a single methyl group from tetrahydrogestinone. That last one cannot readily be made from a commercially available API as far as I know but as with 'the clear', I suggest that they bet on the tiny doses needed would not be detected, hence, 'the clear 2 - this time it's expensive'.