How Big of a Difference?

I think you have to allow for both sides having some correctness in their position. In other words, cables can act as mild tone controls - some may sound a little different than others -- but the difference between cables, in terms of the cost relationship between standard and the higher end cables, is nowhere near the differences you can get with different primary gear - speakers, source, amps.

Also, in general, cables may sound slightly different, but that does not mean expensive ones sound better than cheap ones. This isn’t gourmet food or wine where rarity is created by the quality of the delicacies. This is manufacturers creating culture around their products to create a premium perception.

Also, just because someone has thousands of posts on Audiogon and speaks with complete certainty doesn’t mean they are correct. It just means they post a lot and that’s who they are. There are lots of people in this world that speak with complete certainly about total BS. That is not to say that cables have to be total BS, but just don’t let the tone of one post convince you of anything other than as it relates to the personality of the poster.

EDIT: to clarify, the above refers to analog cables. On the digital side, people tend to misapply analog logic to their digital cables...and hallucinate major differences that from an engineering perspective cannot be there. [And yes, fine to apply the paragraph above to my opinions as well!]

I always love the "your system is not resolving enough" commentary.  Frankly, any reasonably eared person should be able to detect differences on almost any system, resolving or not, IF there is a difference. It's the delta you should be able to detect, regardless of the quality of the starting point. The "resolving" comment to me is a defensive rationalization.

My usual response that statement is "or maybe your brain is not objective enough..."

I do not mean to attack those who responded in good faith, but I do want to point out to those who regularly post such statements that really they're putting themselves, and their fancy dandy systems, above other people.  It's a bit condescending.