Hard to say...no way to dispute his claims, arguments on both sides can be made
Bob Hoffman claims that shortly after Zigler invented D-bol in the 50's , many of the top guys at York and southern Cal, started on it soon after.
The amounts and types of PED's were limited until the late 60's and early 70's.
I met Chet Yorton at an AAU show in Mass., over 30 yrs ago. Quite a gentleman, soft spoken, intelligent and a class act.
I asked him about the drug issue and he was very matter of fact about it.
He said he passed blood and urine tests and had nothing to hide. He then shrugged his shoulders, smiled and said;" What else can I do , if folks don't believe me, I can only them my test results and word as a man."
I then picked his brain for some great diet tips and practical techniques to get a better pump when training.
He loved talking training and how to get a huge pump.
He had some impressive forarms and a "movie star" , well groomed, look to him.
I always wanted to compete in one his drug tested contests, but his organization never really took off.