Some easy to identify physical hints at detecting steroid users:
1) Unusually greasy hair or oily skin (often with stretch marks on the inner joints)
2) Small red or purplish acne, including breakouts on the shoulders and back
3) Gynocomastia, the abnormally excessive development of the breast tissue in males
4) Persistent bad breath
5 Increased length and thickness in hair (on body parts other than the head)
6) Jaundice or yellowing of the skin; this signals liver damage
7) Skin eruptions and infections, such as abscesses and cysts
8) Fluid level changes, bloating (face & body).
9) Rapid or progressive weight gain
The easiest ones to detect in baseball players - IMO - were #6 and # 8. And most particularly #8.
Muscles that seem almost "puffy" - and yellow eyes - were what I saw most in college athletes and pro players the last 10 years.
Then - in a year or two - the muscles are gone and the yellow is out of their eyes.
From Troy Glaus to Lenny Dykstra - from Barry Bonds to Jason Giambi - if you saw them in person - you knew something wasnt right - regardless of how they played on the field. Freakish puffiness in the muscles - especually those around the chest/breast area - and a yellow tint in their eyes and skin.