Past employment as a fitter, foreman, leading hand, hire controller and manager of several “equipment hire depots” I have experienced many a bad batch/box of spark plugs. Wether they are precious metal or not, I have always thought that premature failing of plugs was because of the porcelain failing due to poor quality control of that component in its production or because of “over crimping pressure” of the metal body onto the porcelain body(that causes the porcelain to fracture and so produces a leak to ground of the coil discharge). When I was a boy, I developed a simple test to prove this the theory about the leakage of the invisible monster that bit me several times. Allthough I use the Guzzlerdore these days as the main test instrument, the test still remains the same and every dud and every box full of duds is quickly exposed.
