My band mates did a nice cable article for Premier Guitar Magazine, link below, and I tried some of the demo cables. There were clear differences in sound- detail, frequency response, smoothness. The differences were minor compared to the many other factors that affect the sound, but definitely detectable.
i went there looking for the measurements, the spectral analysis, the double blind tests. instead i found:
"In the end, though, we felt that experiences with cables are inherently subjective – they’re not something that can be measured in a meaningful scientific way.".
-- We make a living from what we get, but we make a life from what we give. - Kathy Moser