I don't know. I've read posts that claim static from the carpet is an issue. Some people suggest that resting against carpet influences the cable capacitance (the "air is the best dialectric" argument). Other posts say that vibrations from the floor affect the cable and influence imaging. So apparently no one else really knows either.
But many people claim to hear a difference using lifters, even those made from wooden chop sticks tied together. So this can't be dismissed as a case in which someone needs to hear a difference because they spent $300 on a tweak.
Do a search in audioasylum. There are many related posts.