Cable isolators ???

Can anybody (preferable someone not trying to sell them) give me any feedback on how effective cable isolators are?

Are they most effective on speaker cables, interconnects, etc.??

Do they work better on floors, carpeting?

Is this just a ridiculous idea??
Very interesting advice. Thanks. I guess I was under the assumption that because cable isolators were ceramic, that the problem was due to static electricity (hum) more than vibration. Great ideas. Thanks.
The dielectric characteristics of foam are much more invasive than ceramic. I have used teepees and ceramic in previous systems, and I like the ceramic better.

Carpet is a dielectric that DOES effect the ability of cable to transfer signal.
I use cable isolators on both of my systems. They are used only to keep speaker cables and power cords off the carpet and route cables away from each other. Although they do not produce a dramatic improvement in sound, they do tend to slightly deepen and tighten bass and lower the noise floor. I would rather have them in my systems than do without. I would gladly purchase them again...
I use a set of audiophile cable insulators to lift my speaker cables off the carpet. They make enough of a difference that the day I put them in, my wife came home from work while I was listening to a well-recorded CD of jazz vocals and the first thing she said when walking through the door was "Did you change the tubes today? That sounds really good." So in my system it makes a real difference.