What do you like and dislike about vintage Western Electric cables?

Technically cotton has a lower dielectric constant.

I am not sure I abide the theory of dielectric polarity alignment, and hysteresis… but it is not like they could improve with a battery biasing scheme.

I do not know what to listen for to prove that though.

The vast majority of WE wire out there is okay, but nothing that special.  Wire pulled out of phone switchboards fall in this okay category.  Some wire from the 1940’s and earlier do sound extraordinary, but this wire is quite rare.  I heard such wire in comparison to Audio Note Sogon, and it was surprisingly competitive.  I prefer Sogon for interconnects, but that stuff costs quite a bit.  

We joke about having to wear gloves to handle the old WE wire, but caution is warranted.  Some old wires were treated with arsenic to reduce damage from being eaten by vermin.
 

@holmz - Most of the vintage WE wire being used to construct cables is stranded tinned copper and actually has a pvc dielectric with cotton over that.  The wire most commonly used is the vintage KS13385 Hookup Wire, which is still made and can be purchased new.  A smaller percentage of the wire I have seen being sold has direct cotton or silk dielectric.  You see this (often solid core) wire used for ICs occasionally.

IMO, with vintage WE wire it is about the tone and midrange body.  The wire is mostly tinned copper (like Supra cables) and I suspect that and the annealing process have a lot to do with how it sounds.  IME, it can be used to make very nice sounding power cables.  I have two 7 awg WE wire power cables powering my monoblocks.  It also works great for speaker cables.