A PSU cable tester is valuable for this. They're much cheaper than a replacement PSU, and you can plug in cables wherever they fit on a PSU, and test whether the output is correct for the CPU/PCI/motherboard/SATA connector you want to plug it into. The PSU and cable might be a black box, but the output is always testable.
Couldn't you still fry a PSU if the cable assumed multiple common pins to the PSU, but the PSU had different voltages across those connectors?
At least for the layouts listed here: https://pc-mods.com/blogs/psu-pinout-repository
The motherboard cables do all kinds of different scary crossovers so never separate them, though you'll probably never have an "extra" motherboard cable in the first place.
None of the other cables bridge pins on the PSU side, they "just" scramble the pins they're attached to at the other end.