HI Morimoriya 62,
While your cables are not made my ALO I can talk about this issue with some experience. Your cables appear to use a PE (Polyethylene) jacket. A PE jacket can over time turn silver plated wire green in color or darker in color. The greening is called galvanic corrosion and while it sounds bad I have yet to see a audio cable that was impacted by this discoloration. From my experience as a long time cable maker this can happen when a PE jacket is used. While it does not alway happen in the right environment this can happen, PE jackets can let in moisture and sweat. Also with my experience as a long time cable maker and cable listener I can tell you that the cables that turn green like this are not effected sonically by this discoloration. I have done extensive cable autopsies of green wires under microscopic examination and the green you see I was able to brush off and expose the silver underneath. While it does to appear to effect the cables sonics it does "look" bad and therefore there can be some psychoacoustic effects

. Because of this ALO uses FEP jackets or medical grade PVC with stranded wire that is enameled or coated to seal the metal from the air to prevent this discoloration. I like the sound of PE jackets but because of this problem we do not use PE jackets much anymore.
It looks bad but it should not effect the sound. While I do not what to defend a competing cable company

this is the facts as I know them.
I hope this helps!
Thanks
Ken