Yes, lifting the speaker cables off the floor often times make a very audible improvement. But it's also like bi-wiring a speaker.
It has everything to do with the type of cable, the resolution of the system, the ears of the listener, the height of the lift, and perhaps the type of carpet.
Just because somebody does not hear a difference does not necessarily mean there are any shortcomings. But then again not hearing any audible improvements may have everything to do with one or more shortcomings.
-IMO