Is "poor perspective" the barn's inherent bad perspective or the painter's bad perspective? He supposed "If he were to make an accurate drawing..", then why did he say the result is "poor perspective"? That's why I doubt if it is the inherent one of the barn.
ex) One of the main principles I follow when I draw outside is not to select a subject that is too difficult or odd . I try to stay away from houses or barns that have unusual angles of the roof, or objects that look incorrect in size, perspective, or design. If the subject is confusing when you look at it, it will be more confusing when you attempt to draw it. I know a beautiful barn where the corners are not at right angles. No matter how many times I have drawn it, the perspective does not look right. If I were to make an accurate drawing of this barn and put it in a show, Iím sure I would get all kinds of criticism for my poor perspective. I would not be there to tell my critics that the barn is actually constructed this way. So, I stay away from subjects that do not look right to me.
The barn is constructed poorly. The angles are not square.
If he painted it accurately, people would think it was a normal barn and he didn't know how to paint very well.