Actually, I disagree with Sidssp in that all speaker cables, interconnects, and power cords have many properties and electrical characteristics that can be easily measured and don't change very much over time. They all have a certain resistance, capacitance, and inductance, some are shielded, some aren't, they use different metals, solder, connectors, and dielectrics, not to mention they can be wound a myriad of ways. All these factors and more contribute to give different cables their own distinct characteristics.
If cable A sounds "brighter" than cable B in one system, then the chances are highly likely that you'll hear the same repeatable result in other systems (especially if you keep the other associated interconnects and power cords the same from system to system).
None of the cable's physical or electrical properties change when you put it in another system. Only the system changes, therefore, the cable itself sounds the same.
As a matter of fact, my Magnepan system has been sounding a bit bright since I made some recent power cord and interconnect changes... So I'm going to put in some warmer, less-bright copper speaker cables to see if that tones things down a bit. I'd be very surprised if it didn't. Cheers!