>ice theory, but this 'ere really good quality Sony cable will not charge the wife's crackberry, while a skinny, fourpenny fleabay job plugged into the same PSU will.
Is the cheap fleabay cable wired for data? Some devices will charge faster if they spot that the data pins are shorted, i.e they will only draw 500mA if they spot a data cable, since this was the spec for computer USB sockets. The Sony cables will be data cables. The fleabay cable might be power only. Newer devices will happily draw 1-2 A over a data cable, if the power supply is up to it. (Phones power supplies are typically 1.2A - 1.5A, tablet PSs are usually 2A)
Whilst it can be hard to spot which cables are of a decent gauge, short cables are obviously easy to identify.