Usualy if someone looks like they may be on, 9 out of 10 cases - they actually are. Look for shoulder roundness especially, and condition WITH some size (but everywhere, not just on one or two muscle groups, which may be a stregth genetically). Just recently, one fella I know, ~40yo, all conditioned, not big, but FULL. Asked about that - he declined instantly, even tol that he wasn't in the gym for a few weeks because of sickness (oh "And he started taking some otc supplement that should increase test production naturally"), just shook my head.. a fukkin filt.