im not an export on juicing but it allows you to work out longer, recover faster from injuries, more endurance etc things along that line. it allows you to work harder and more often, gives you that extra capacity. I see it as a way to take someone to "the next level" for an experienced bodybuilder that is maybe seeing some slower gains. If a 16 yr old kid took roids and did nothing but sit on the couch all day, he would not suddenly gain 30 pounds of muscle and double his squat/bench/deadlift. Some would say it tarnishes your reputation but again its effects are exaggerated even with roids his physique is pretty amazing no homo. sorry if my posts aren't very articulate
there is this study "The Effects Of Supraphysiologic Doses Of Testosterone On Muscle Size And Strength In Normal Men" where worked out and ate properly and they gained less muscle than someone just living regularly on steroids 100% srs. OBVIOUSLY it's not like you get on it and bam overnight you're jacked. but people really do either overestimate what can be done naturally or underestimate how much high test levels can help.