Yes, Battery Cables do go BAD.
A friends Ford Exploder wouldn't start in the parking lot of work. He had someone else helping him and the new starter still wouldn't engage. They were already removing it and take it back to the store, when I suggested they check the continuity/resistance of the battery cables. Even though the cables looked fine, the resistance was almost infinite. We hooked up jumper cables to the old starter and it spun right away.
If you do a google/froogle search you can find all the various parts for battery cables, the different terminals and cables, so that you can put together you own custom set that would fit perfectly.
The only problem with that, can you beat the lead terminal that is molded around the cable for reliability? There are copper (coated) terminals out there that you can crimp like regular smaller terminals. These terminals are showing up on OEM battery cables. I would think, if your going to make them yourself from universal terminals, making a good crimp with a copper terminal would be better than a universal lead terminal, where you clamp together two pieces of lead, trying to squeeze the copper cable between the soft lead pieces? Anyone with some experience with the two.
I've used the universal lead terminals in other cars, although I never had a problem, the appearance of the connection didn't inspire any confidence. Not like the crimped on connectors you see with sheet metal or copper terminals.