Interconnects, some have directional indicators, why?

I'm just guessing here, but I imagine it also may have something to do with the magnetic fields which are created anytime current moves (right hand rule) down a conductor.  I imagine that the geometry of the conductors are used to manipulate this in some way that they feel impacts the signal the least.

Then again it could be pure snake oil, but I doubt it.

The problem is that wire is directional. All wire, wire in fuses, wire in interconnects, speaker cables, internal wiring in electronics and speakers, the wire in capacitors. That's why interconnects that are not shielded sometimes have arrow, you know like Anti Cables and others. So, here's the real problem, those cables and interconnects that are shielded and have arrows to indictate the direction the cable should be connected because of the shield may or may not consider the direction of the wire itself. It doesn't take a rocket scientist to figure out the wire in shielded cable should also be considered when marking the cables for direction with arrows. The sound would suffer somewhat if the wire itself was in the wrong direction even shield was in the right direction.

The comments regarding the shield being connected at one end only are correct.

Obviously since the audio signal is an Alternating Current signal, the actual wire is not a variable.

What may be a little confusing is that not all RCA cables are balanced + shield, but are in XLR.

In other words, the better RCA cables have two identical conductors, except the insulator color, typically red and black. One goes to the center pin, the other to the outer ring.

In addition to these there is actually a third conductor, not identical. Best are an impossibly thin foil shield, which is in contact throughout it's length to a drain wire. The shield is impossible to solder to, so we use that drain.

So, red and black connect at both ends. The drain however only at source.

Cheaper RCA cables use 1 wire, plus a braid. The central wire goes from pin to pin and braid does double duty as signal and noise.

There are minor tradoffs as the shield adds capacitance while preventing noise, but it's usually well worth it.

Best,

Erik

^^^THIS.