Unfortunately, skills aren't the only things passed on from "Tradesmen" to the apprentice, if a roofer has never been taught the proper way to install a shingle, he teaches his entry level guys the same junk... Then they teach the same thing... And so the vicious cycle endures. The biggest problem I see, is that a lot of general contractors don't supervise their subs and if the work is to code, an inspector will pass even if it is shoddy(ie: boards cut a little short, missed nails, etc...) Don't even get me started on SOME of the so called "Home Inspectors" out there!