High End Ethernet Cables ....Real Deal or Snake Oil

Digital streaming and network-based storage systems are now mainstream. I have notice more and more cable companies are coming out with 'fancy' Ethernet cables ranging from $25-$2500. 

Purist Audio, Cardas, Chord, Wireworld and Stealth Audio to name a few.  I am assuming, AudioQuest is probably the first manufacturer to recognized the potential for a fancy Ethernet cable and started this trend (sorry no offense to anyone). 

Let's for a moment assume that there is a audible difference in sound quality when streaming music files from a NAS or intranet to a server. Ethernet is an error corrected transmission protocol, it is going to be bit perfect. Are these fancy cables banking on the same principles of other digital (SPDIF/XLR) cables ~ a well made cable reduces the margin of errors resulting in less requests for re-sends, and if there are less errors and subsequent re-sends, perhaps this higher performance results in less noise, fewer dropouts at the receiving end, and subsequently better sound quality?

I do not know a lot about networking so I chose an easier path to stream music in my rig. My setup involves a music server, DAC and Apple Extreme base. 

I am wondering how many of you using a high end Ethernet cable vs. a generic Ethernet cable. 

Is there a test data or device that tells us how many errors and re-sends happen in Ethernet data transmissions to justify the use of uber 'pricey' ethernet cables? 

Thank you all for your feedback!