Some suppliers recommend to use the original micro-usb cables for usage with there device. One example is syncing via Samsung Kies. I also exerienced that some devices seem to be realy sensitive to the cable used. 

Where are the diffences comeing from (e.g. shielding, capacity, resistance)?
Are different 'quality classes' for micro-usb cables defined? When I want to by a new cable, how can I be sure that it will work with all devices?

I'm more concerned about the Quality of data transfer, than on the chargeing time.