Yes, they do wear out eventually. As pointed out already, the life time depends greatly on use and quality. Even with a cable that seemingly works sound quality may get drastically reduced. See below.
The type of defects you will start to see over time, can be categorized into three main areas:
I have done this sort of thing before. I have use good, resonant kitchen knives or a long blade/sword. Slide them against another blade for the ring sound for stab in and out. Maybe try to mount sheet metal or two pieces of metal close together and slide the blade in between them. Then use metal cutting scissors and cut the metal for the metal "crunch" sound ...