Do expensive guitar cables make a difference?
Absolutely. Aside from any capacitance benefits, you can reasonably expect higher-end cables to have had much better levels of quality control across the manufacturing process. They will be less likely to fall apart on the inside, resulting in serious degradation of signal.
Do gold-plated guitar cables sound better?
Another marketing ploy is the “gold-plated” connector instead of the normal nickel or silver ones. In reality, gold-plated connectors are just better in performing against corrosion. They last longer than the nickel or silver ones, but this has nothing to do with the sound quality of a cable.
Does cable length affect tone?
To keep it simple, think of it this way: The longer the cable, the more capacitance is introduced. The higher the capacitance, the less high-end in your guitar tone. One way to deal with this loss of high frequencies is to add a buffer pedal to your signal chain.