I think that if you have a whole chain of top shelf leads, acc etc etc, it might make a difference. But, the problem is some people believe that one good lead alone will do something magical, then myths start up, and so on. I bought monster guitar cable, expensive stuff, and hated what it did to my sound. The cheaper monster 'rock' cable and mogami sounded so much better - more suitable to guitar.
That expensive cable gets used occasionally for bass tracks though, so it wasn't a waste of money - can hear the difference in some applications.
I guess I'm saying that there's usually some truth to the myths, that's why they sound so believable.
Having said that...I hear a lot of stange stories about magical power cables (for amps), leads, etc.
Anyone know much about the monster power lead? Very very expensive but why?