My take on double blind tests is that it's easier to design a dbt for medicine than for audio. Perception is a funny thing, and the brain is a lot more sensitive a processor than it's generally given credit for. Sometimes it happens on levels you don't realize, tho, and so testing for it can be tough. Especially with things like harmonics. If someone ever designed the right test, it'd be worth discussing. 15 second clips of audio through a switch box, etc, probably aren't the right test.
And the clever little clock people aren't idiots, they're geniuses. They're making a mint selling to idiots, but they're just good at marketting. I don't believe there's any way at all they believe the tripe they're selling.