"Hey, after all, I'm a professional, so I know how to break the rules properly!)"

Like the shoemaker with holes in his shoes or the carpenter with a hole in his roof.

I have a buddy who is an electrician, at who's house you can see some of the most horrific uses of extension cords, temp lighting and countless other electrical odds and ends used in a way that a professional (that he is) should always be on hand.
I laugh (probably should cry) to myself everytime I set foot in this guy's house.