Heh, heh, the worms are already wriggling! ;o)
I just found this on the Chord Company website (referring to their Rumour product):
Rumour is very difficult to directionalise during blind testing. We recommend that the cable is fitted so that the print on the cable runs from the amplifier towards the speakers, but should this not happen, it is best to leave the cable as installed. The direction that Rumour is installed in when new has very little effect on sound quality. However, with cables that show very few directional characteristics, this can change as a current is passed through them. Once Rumour has been installed in the system, whether in the correct direction or not, changing the direction will be detrimental to the sound of the system. There is not really a good explanation for this but as a statement, it could be said that "Cables that are not particularly directional from new will become so when used, and cables that are very directional will not sound right if installed in the wrong direction".
Interesting. Makes you wonder about buying your cables second-hand, eh? 😱)