Without going over the individual cases:
- Do they compete in fitness, are they sponsored, are they a model, are they an actor preparing for a role, are they an athlete?
- Does their body "transform" seasonally, or has it transformed from what it was when they were already training, with no explanation but #hardwork and #diet?
- Are they both cut to a low body fat
and ripped with "full" muscles?
- Do they weigh more than what other people who train and are of the same height and build do?
- Do they make a point to talk about how "natural" they are and other mantras like #whatsyourexcuse, #hardwork, #dedication, etc.?
- Are some of the upper body muscles with the most androgen receptors in them (traps, delts) or other muscles proportionally bigger than they look like they should be?
Those are some of the hints and signs of a fake natty, some indirect (they're a top athlete) and some direct (their shoulders are "capped"). There's
plenty more. Also, just because someone doesn't necessarily look like they're taking drugs doesn't mean they don't. They can be taking lower doses and/or having a poor drug response, and/or problems with their organs.