To someone who doesn't know anything about network cabling, cat3, cat5, cat5e and cat6 all look the same. 4 twisted pairs terminated with RJ45 connectors. The materials used in construction are different enough however to allow the correct cables to perform at higher specifications.

It was just an example. A cable for any purpose made with inferior materials may or may not be suitable for the intended purpose. I have a number of SVIDEO cables here that would be visually similar to most people yet I can clearly tell the difference between them when used. Most of the sets were actually the same price - just different quality materials. Then I have another one which is only slightly better than the others but cost 3 times as much.

I wouldn't pay $100 for a 5 foot HDMI cable. But I'd make sure that whatever cable I was getting was of good quality, regardless of price. Quality construction and quality materials. Good copper, solid soldering, good jacket and of course quality and durable terminators/connectors.

With an internet purchase it comes down to the reviews of other people to have a clue about this stuff ahead of time. In person even when something looks good, you will still have to test it for the final word - but it's much easier to return.

I hate the snake-oil approach to interconnect and accessory sales, but it's important to keep in mind that the quality of cabling does play an important role. Once you've achieved that minimum spec however, the voodoo attached to esoteric items isn't really going to do anything for you except drain your pocket book.