There is no snake oil. The reason cables sound different (yes they do) is that with low analog signals (passive guitar pickups for example) their capacitance is not negligible. They basically act as filters. So the observations like 'more clear high end' etc is basically related to capacitance difference. Of course length also matters. If you change the length, you change the capacitance. If you want more highs, try to keep the length short.
Snake oil? What has oil to do with cables?