back in the 80's, I worked out in a gym with both professional athletes and Olympic hopefuls. Even though no one admitted to taking steroids, when you see someone every day, you pretty much know. In addition to the above characteristics mentioned by Dancer, you can add: a certain tightness/squaring of the jaw in both sexes. Deeper voice and beard stubble on women. Also completely disappeared boobs and butts. On men, it was the perpetual second stringer who suddenly could do things he had never been able to before, despite no discernible change in his workout.

It was like the secret rhinoceros in your kitchen -- kinda hard NOT to see!
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