There have been many tests on cables done over the years.. They have shown no difference (not even a little) that there are $7 dollar cables that equal $4000 cables. One test a green banana performed well !
For those who refuse ro believe these tests, a more specific double blind test is effective. Either you can hear a difference or not. An expensive cable that "clearly makes sound improvements" should be easily detected. This method also has shown the cables are indetectable between them.
After all this, are a lot of people who still swear their 'expensive' cables are worth spending the money.
The guilt trip... after you spend God knows how much money on an expensive system "you'd be a fool to connect it using cheap cables!". Another one is... "the better the system the more you NEED expensive cable".
The real root of the problem is the human brain is very suseptible to bias. There are 12 types defined as cognitive bias. This is the real problem. Even proper double blind tests will still be viewed with scepticism due to bias suggesting there's been foul play. Conspiracy theories are easy to implement due to this weakness.
It's an arguement you can't win.

