Someone cared to downvote. So I made a random Google search and came up with this guy, who is 5'8 and 210 pounds in contest state
http://www.bodybuilding.com/author/john-hansen
Which puts him at 31 BMI, so just barely in the obese category.
And this guy is clearly not your average "gym rat", he's a winner of Natural Mr. Universe, so he'll be somewhere on the very edge of the Bell curve. 99.9% gym rats will never be close in terms of lean body mass. So if they are "lumped in obese", then they truly have a lot of fat to lose.
Not really. To get to obese by gaining muscle mass one would most certainly have to use certain illegal drugs.