Hi Felix,
Very good point. We all run into a bad cable during our travels. A bad one is, as you said, easier because it just doesn't work. The intermittant ones are buggers. I remember years ago troubleshooting an Win-98 machine with an ASUS MB, that every 3 months, would on boot up, stop at the setup screen as it didn't see the boot drive. It was set up with a SATA HDD with the system & boot partition, and an IDE as a secondary drive. When it reset, it looked by default for the IDE drive first, the one without the OS. After a lot of head scratching, I replaced the IDE cable (Master SATA & DVD) and never had a problem after that.
It is a good point to always keep an extra SATA data cable, IDE cable, USB cable, etc in the toolbox, so if there is any question, you can swap out a "suspect" part. And if it doesn't help, swap it back in!