Objectively cables don't really matter as long as the electrical properties such as resistance are in the reasonable range considering the usage. Of course it matters if you try to use say 10 Ω cables with speakers. It will definitely affect the sound in a nasty way, but who does that? Snake oil doesn't lower the resistance, which is:
R = L / (σ*A),
were L is the length of the cable (in meters), σ is conductivity (A/Vm) and A is the cross-sectional area (m²) of the cable. You don't see snake oil in this equation. Nor do you see snake oil in the equations for capacitance, inductance, skin effect etc. Audio cables don't even behave as transmission lines, because they are not kilometers/miles long and 20 kHz is the highest frequency we have to worry about. Audio cable are relatively short and operate at relativaly low frequencies. That's why audio cable are not that demanding except for mechanical durability perhaps.
Subjectively cables do matter to some people, but not for the reasons these people assume. The real reason is placebo effect running wild not restrained by the objective facts above, but instead amplified by the marketing speaches of snake oil sellers who take advantage of weak minded ignorant people.
Unless you are a very wealthy person (millionaire/billionaire), your resources are limited. Use the money wisely were it matters the most. One should invest tons of money into acoustics/speakers/headphones before even
thinking about cables. After you have superb acoustics and superb speakers positioned optimally in your room is it time to think if you should upgrade your speaker wires because skin effect and resistance of your current wires perhaps causes 0.2 dB dip at 20 kHz. Maybe not, because you can't hear much anything above 16-17 kHz anyway. However if the same thin cable causes reduced damping factor, upgrading the cables (not snake oil, but thicker normal cables) might improve the bass.
The most expensive RCA cable I have ever bough was the cheapest Cambridge Audio cable (17 euros). It doesn't sound any different from cheapo RCA cables, but it is mechanically robust and reliable which the cheapo RCA cables are not. It has served me well for almost 2 decades between my CD player and amplifier. Most of my RCA cables are DIY cables which is a good way to get reliable relatively cheap (~5 euros) cables at correct (shorter) length.