Does raising speaker cables off the floor really make a big difference?

@simonmoon  "  He likes those porcelain ceramic insulators. They can be found for a lot less money than the ones made for audio."

Isn't this a bit of a tip that some audio vendors can be quite predatory?
Also, I am suspicious of any tweak that is reported to take a few days or weeks to deliver it's benefits. That makes A-B comparisons extremely unreliable and magnifies the probability of user bias developing.