One reason blind (or double blind) testing is controversial is simply some folks won't admit that the $500 (or more, sometimes much more) cable they just bought doesn't sound any different from the cheaper brand.
Let's face it, the guy who says his jaw dropped when he installed his newest (and more expensive) piece of equipment, and then can't id that same piece when he can't see it is the reason blind testing has never been accepted.
I believe there are differences between some components, but not to the degree some people claim.
Although I have nice components, including all tube electronics, planar speakers, and listen more to vinyl than digital, I have never cared for spending hundreds or, in some cases, thousands of $$$ on cables, power conditioners, or power cables.
From all I've read, not one double blind test has ever given credibility to audible differences in cables.
What really gets on my nerves is someone who starts describing the differences he hears with components auditioned weeks or months apart. Sorry, our auditory memory usually doesn't last more than a few moments.
Jim