nuintari's rules of networking 0x2c:
Never scrounge a cable out of the trash. It's in there for a reason.
1st Corollary:
Always cut any cable you're throwing in the trash to prevent breaches of the aforementioned rule.
2nd Corollary:
If you replace ends on a trashed cable without also running it through a tester, you deserve any and all of the pain coming to you.