"The fact that this is bad design practice is not questionable in my opinion. Ask ANY mechanical design engineer and he will tell you the same."

Me, I can't STAND C-arf and their ways, but I still have to disagree with the statement above. If the structure was designed as a stressed skin deal, I supposed the spar material is irrelevant, all it needs to do is keep the skins apart at the proper distance.
Now...if that spar is actually supposed to be load bearing, now...that would be pretty frightening...