It's being able to actually quantify these differences arrived at through characterization why people who understand the tech will accept audible differences in some cases and not others. There is a reason companies like Kimber and Mogami list electrical specs.
We also do things like hang cables a few inches from a speaker at high volume and measure the signal with a typical preamp/amp impedance to show that vibration typically has no impact. Maybe we measure the voltage on a cable just sitting there with a typical preamp/amp impedance to show that it is near 0 debunking crazy notions of "static" voltage that require burn in to fix.
They should be able to measure Home Depot zip cord and ANY cable from any other manufacturer and prove that the output from any of them is exactly the same as the output from all of them.
We also do things like hang cables a few inches from a speaker at high volume and measure the signal with a typical preamp/amp impedance to show that vibration typically has no impact. Maybe we measure the voltage on a cable just sitting there with a typical preamp/amp impedance to show that it is near 0 debunking crazy notions of "static" voltage that require burn in to fix.