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

I have to go wit the "made no difference at all" crowd. I have tried this in my systems as well as having others I know try it. Not many of us as there were only four total but not one of us heard a difference. And if there was actually some difference it was not audible, and certainly not worth the price of any expensive cable elevators. The most common method used were wood blocks, and all of us tried the Cardas elevators. Again, like everything audio, it is so system, room and home  / environment dependent. One just has to try it on their own, or get enough feedback from places like here to make your own informed decision.

"3. which direction the fibers are vacuumed in vis-à-vis the cables lying on them."

If you have not been vacuuming in circles, you have been doing it wrong all this time.

Well shoot!
That's why I have crop circles in my deep shag pile!

😉😉

Shagadelic, Baby! Yeah! 🤗

No.