How far back in boxing's history do we have to go back to when fighters first started accusing their competitors of getting unfair supplement advantages? Prior to the 1990s were there boxers who got accused by other boxers or even fans? We should keep in mind of course that PEDs existed well before the 90s.
Maxine Cates (Dempsey) said that Jack liked the Booger Sugar before a bout and that's why he faded after 4 rounds.
The first time I had heard about steroids in boxing was in the case of Bob Hazleton. Bob was a journeyman heavyweight whose biggest claim to fame was knocking out the washed up Bob Foster. But it wasn't during his pro career but afterwards when he got into body-building, which is a completely different animal. Bob was juicing with his newfound passion and the story goes ultimately lost both legs due to steroid use. This was the first time I ever heard it mentioned in the same breath as boxing, but again, it was post-career usage.
I know steroids were around for a long time and probably used by boxers here and there for decades before it came into the more popular lexicon (I’d especially suspect East German and Russian Olympic boxers because their countries had extensive steroid programs that used athletes like lab rats), but the first high-profile guy I remember being busted for it was Shane Mosley. He was part of the Balco scandal that rocked baseball and other sports and iirc failed a test for creatine.
The Russians are believed to have ushered in the age of modern sports steroid use in the 1950s initially with their weight lifting teams. It wasn't until the turn of 21st century when testing/investigations actually became widespread, where you had guys like Mosley, tons of MLB players and then guys like Lance Armstrong getting busted. Russia was recently banned from Olympic gymnastics because one their 14 year old girl gymnasts tested positive.
your mention of the East Germans had me recalling the ‘76 Olympics when the East German “women” cleaned up at the swimming events. It was obvious they were all built like men but it wasn’t until the competition was over and the girls were singing that some sharp-eared reporter got his mic close enough to catch them live that they all had the deepest, guttural voices they had ever heard. All derived pharmaceutically of course.