I think the question is whether we are talking about the proverbial 90 pound weakling like on the Charles Atlas ads or what....
You take certain guys and put on just a LITTLE muscle but manage to shed a lot of fat while preserving that muscle well and they could look a lot more "jacked" to you...especially if you weren't seeing them on a day to day basis but only saw the before and after. And of course we need to know what any one person means by "jacked" in the first place.
I have a non-training friend who compared to me when I started out (the many times that I started out
) is a lot more naturally bulky in terms of muscle. The only reason he doesn't look jacked is a little bit of esthetic detail and a lot of fat. Sure he has a good layer of fat overlaying his muscles but the basic jist is he is a lot more muscular than I would be if I didn't train. I could be wrong, but in my mind, I would picture putting a lot less muscle on his frame and then losing the extra fat for him to be pretty jacked...compared to what it took for me.
BTW, it seems to best way for prisoners to get roids in prison is through the prison workers. Profitable place!