I agree the cable probably is crap. It usually doesn't matter so much because devices have a battery to supply and charge instead of directly powering devices, so one does not notice such cables because they work with other devices.
But I am a bit disappointed that @jamesh responded the way he did. It would be an easy and logical fix to increase C1 for the 'W' and make it more stable in corner cases like these. Mind you, for myself I now know about the issue and can deal with it. But I bet there will be another user with another crappy cable that will loose hours of his lifetime over the same avoidable issue.