Part of the problem here is that it is virtually impossible to tell who is and who is not on drugs by looking at them, except when combined with bodybuilding. Those who work out have surely seen those guys who grow and shrink like balloons as they go throught there cycles.
But there are plenty of guys who I have trained, who used steroids who were darn skinny and didn't get all that much bigger...they were still skinny...look at Petr Korda or Coria for that matter.
By that same token, if you see a guy who looks big and ripped, there is about a 90% chance, believe it or not, that he has used....it is extremely uncommon to get that way naturally.
As far as Hewitt goes...no way to know...I think it's widespread anyway, but his appearance change is not unnaturally dramatic and could certainly have been achieved naturally...so I don't think he's a more likely suspect than he was 2 years ago!