There are SEVEN major issues with speaker cables that must be addressed well; Inductance, Resistance, Capacitance, Magnetic field cancellation, Electric field cancellation, Skin depth, and wire quality.
Few speaker cables address all seven correctly and throw in wire quality (actually well down the list compared to the correct DESIGN) and a few buzz kill "trust me" engineering phrases. Most cable get their "sound" from poor engineering that disrupts phase coherence (too high capacitance) or slew rate limits the current transients (too high inductance). Some even have to use extra circuits to offset a variable that was left out in the cold in a bad design (sky high capacitance to get low inductance, for instance, using a Zobel network).
A good cable design should have low capacitance (less the 50 Pf/ foot and low inductance (less than 0.15uH/foot. The resistance should be at least a 14 AWG to avoid effecting the speakers cross-over characteristics. Too high a resistance allows the speaker output response to follow the low frequency impedance curve, which is usually, non-linear. The skin effect at audio is about 18-mils deep, so at least 18 x 24 AWG wires are necessary to properly allow current distribution at ALL frequencies across the wires. I say 24-23 AWG as the skin depth at 20 kHz isn't too important but 10 kHz is, and that allows 23-24 AWG wire to work well. Some compromises must be made to get the cable made and eighteen wires is a lot to manage. EVERY cable is a compromise, some are just more evenly designed than others. The B and E field cancellation requires closely spaced wires (b field) and proper electric field cancellation (insulated wires cross at an angle to one another).
Few, few cables really do what they are supposed to do. Ninety percent of what you hear is a good DESIGN, and NOT expensive materials. Most tout materials as ANYONE can get high priced materials and make you pay for it. FEW can design a cable correctly as that takes a lot of talent and snake oil repellant.
I know from experience that standard grade copper, what is called tough pitch copper, can exceed high prices copper and even solid silver in a good design compared to great materials in a poor cable design. Look for a good design, first, and materials LAST. Standard OFC copper is plenty in the right design. If the cable isn't using 24 AWG or finer insulated wires, silver-plated is a waste of money. You want the silver to enhance both the low and high frequencies, and if the current density across the wire is managed right, both will benefit, not just the "treble".
A bad design will not allow low capacitance AND inductance. Why? The inductance and capacitance are tied to one another in a given design. One moves opposite the other when insulated conductor spacing is changed, for instance. If you have an unbalanced cap to inductance ratio (some cable have 1600 pf/foot capacitance and 0.1uH/foot inductance!), you're stuck with it till you CHANGE the design. Most just let capacitance get too high as these are easy designs, and most don't realize what high capacitance does to imaging stability.
Good designs? Look at NORDOST speaker cables. They get most things right. Yes, they ignore E field cancellation (parallel wires) but the speaker is a low impedance source and MOST RF is not a problem against the high current signal in a speaker cable...if it is, you're screwed as the cable does nothing to passively block RF. There are other good cables, too, but the list is much shorter than it should be.
A perfect speaker cable is a straight wire with no resistance and is infinitely small (no skin effect). It would concurrently pass current in BOTH directions at the same time (no B field energy or E field energy wasting power as they both cancel 100%). This also means it has no inductance. It would have an infinitely low dielectric constant for the insulation (sit in a vacuum) and have no capacitance. This cannot be made, so every wire is going to have a "problem" to some level at EVERY aspect of the design. Most cable can get R, L and C right if they use a simple ZIP cord design, which forgets about skin depth management. The fine management of skin depth and field cancellation with multiple wires is difficult, and makes HUGE improvements in the sound. Look for cables that address EVERY tenant that I mention. Walk away from speaker cables that ignore even ONE meteric for performance.
Shop wisely and listen to the cable. "Coloration" is NOT the sign of a good cable, it just isn't. A speaker cable should be as transparent as possible if it is an ideal transmission line for current signals. Transparent wire is an excellent choice on any speaker. Buy your speakers based on their sound, not the cable's. Can't afford a well made cable? At least audition your speakers with good cables so you don't accidently buy them BOTH. It's all too easy to forget about the cables, which make a bigger inpact than a 10K amp veres a 20K amp to the overall sound. For what they do, cables are cheap. Why buy cable a second time to avoid the "bad" sound of colored sounding cables?
Minor differences in sound, yes. A cable has a finger print based on the seven metrics of design, and how they all interact. The "box" they fit in should be small, however, so every cable will be just SLIGHTLY different if they are made well. NONE should be "bright" or "warm" if all seven variables are taken into account and weighed correctly. Ther is a way too big group of cables that have a warm heavy sounb devoid of a stable clear image across the sound field left to right. EVERY sound should be independant of all others in a good cable. The music should not sound like the fly, where everything thrown in is stuck together in a wad. Good cables don't add "bass" or "treble". Cable just takes things away, as they are passive components. You want your cables to take it "all" away in a linear fashion and to a minimum level (no cable is perfectly good). Good design isn't snake oil, it's called physics. Pay the guys who use it well, they desrve it.