I do know lots of natural guys who train superhard and eat properly and are fitness model-types with great-looking 160lb physiques at 5'10.
The bottom line is that so many guys take gear when they are teens or soon after they start lifting that 10 years down the road, when they are 6' 220, and off the sauce, they claim that they could easily have gotten to the same point without gear. It's a copout. Many of the muscular gains will never go away if you continue to train. I'm a firm believer that steroids raise your body's base muscular weight. If you don't train heavy (a la Tom Prince or Kevin) you will shrink up, but even still, these guys are 5'10 200 lbs solid. Show me someone who's never done gear walking around looking like that and I'll show you a Catholic priest who doesn't subscribe to Blue Boy.
I see natural guys training hard all the time at my gym. The difference between them and the juicers is that the natural guys don't grow! They hit 30 years old and their T-levels start decreasing and they've hit their strength wall and that's it. End of story.