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

Yes.  Carpet static electricity is a real issue, especially where I live. Also bought a "grounding pad" that I touch before I touch any of my gear. And I went cheap and used CD plastic cases. Total cost under $20.  This raised some 70' of speaker cable off the carpet.  Audible drop in system noise floor.  Less noise, more music.  Pretty simple concept.  Whether you can hear or not depends on the overall transparency of your system.

Thank you for the sane perspective. 👍

Static electricity is an issue when you walk across your carpet in low humidity and touch something metal how is it an issue for a cable that’s insulated just laying there or do you rub you cables over the carpet fast causing friction trying to discharge some static?

Excellent question! Now we’re getting somewhere. 

All depends on 1. whether the carpet is wool or synthetic; 2. the carpet's warp and weft; 3. which direction the fibers are vacuumed in vis-à-vis the cables lying on them.