It _is_ possible to build a cable that is so out of spec as to produce audible differences when compared with a normal cable. Indeed, some "audiophile" cables are constructed in just such a manner.
any chance you can provide an example of this? I have not heard of a company purposely building out-of-spec cable. I am not very experienced with cables and such and would like to learn more.
Any company that makes unshielded RCA patch cords is making stuff that is out of spec. Or if they attempt to employ an unshielded twisted pair for an RCA-RCA connection, since those are unbalanced and a twisted pair only works for a balanced connection running into a differential front end.
There are also some rather unusual cable construction techniques that produce cables with RLC values quite different than what is normal. I saw some RCA patch cords for sale a couple of months ago that claimed 720 pf per foot capacitance.
I would imagine that any wire you see for sale in the Mapleshade catalog is abnormal.

With some of these you will actually hear a difference, but I would suggest that it is not a good thing.
Plain zip cord for short runs of speaker wire is fine, and you can get it inexpensively at any number of places, including Home Depot.
The RCA patch cords that come with most DVD players and other mass-market equipment also works just fine. You can get the equivalent patch cords from Parts Express for under $2 ea.
If you really want to get the best quality RCA patch cords around, try the ones from Blue Jeans Cable. Their quality and construction are top-notch. They really are Pro quality, in the best sense of the word. They won't sound any different, but they're actually very nice and will give pride of ownership. They use very good connectors too, so they will maintain good contact over a long period of time.
If you are running cables through conduits or your walls, or if you have really long runs or something unusual, then you may want to go with more specialized wiring. But it isn't likely you will be shopping at the cable boutique to find solutions.
If you really want to learn more about wire, check out the Blue Jeans site. Then try some of the info at audioholics.com.
http://www.audioholics.com/education/cables/Rod Elliott is a good source for info too.
http://sound.westhost.com/articles.htmFrank's old newletter Audio Basics also has some good info.
http://www.avahifi.com/root/audio_basics/index.htm