I've had problems with one long (4 meter) USB Mini-B to USB Type-A cable not being able to boot a 2.5'' external hard disc due to not supplying enough current. On top of that, the cable used a Type-A to Mini-B adapter for the Mini-B part, which probably made things worse.
Three different shorter cables I got around made the hard disk work without extra current, so it was definitively the cable's fault. However, if I plugged the hard disk to the power, and used the long cable just for data it worked.
Here is some related information on powering through USB cables:
I have not any long cables that don't have an intermediary Type-A to Mini-B adapter to try them out.
My question is: is there a way to guess if a cable will provide enough power for charge/disk drive power? Is it related to the length of the cable, to the build quality of the cable, or the fact that uses intermediary adapters?
Updates:
Thanks for the answers guys. The computer is a Macbook Pro 13' (2010), so the USB connector is directly soldered to the motherboard (no front panel USB).
Up so far the most convincing explanations seem the ones from @user12889 (the USB device being over the spec and causing problems because of that) and @Tog (the adapter in the cable causing the power loss), although everybody else provided useful information too.