Age Limit for Speaker Cables

I have had AudioQuest cables which did start to decay. Midnight.. The insulation started getting gooey. Not the outer cover, the coating on the actual wires..
I will never buy AQ again.
Then the infamous Monster Cable wires turning green.

So cables can go bad.

On the other hand, I do use cables which the wires are already thirty years old. i just reterminated them and still use that wire. (Mark Levinson teflon isulation)

As for the materials, certanly modern metals can be better, and the knowledge used is more sophisticated.
However the prices have also risen dramatically. For cables with are the same constructioon and design of twenty years ago.
Kimber KCAG comes to mind. The price is at least quadruple what it was when they came out.

Sometimes cables can oxidize as Elizabeth mentioned about the Monster Cables above. Cables usually become obslete to the listener due to a system change. I have setttled on DNM speaker cables and IC's. DNM has been around for quite some time and has stayed with the same geometry since inception. They use a solid core copper cable and have two types. Precision is for speakers that are >90db and Stereo for speakers that are <90db efficiency.
They will run way less than your 1k budget.

http://www.dnm.co.uk/cables.html

http://www.simplifiaudio.com/online_store/dnm_cables_store.html

I guess this only proves that all good cables, like many other things in life, must someday come to an end! I think oxidation is the primary problem and then there is possible fraying of the actual cover. In the end though, a good cable should probably last you quite a while.
Anyone know if Nordost cables suffer from the same sort of problems? Been thinking of giving their cables a try in my system...