In any other neighbourhood, the Feiyang Times building, a drab grey-and-brown tower in southern China, would be most notable for the gaudy, propaganda-plastered columns that line its forecourt. But like many of the electronics markets in the labyrinthine malls of Huaqiangbei, the fourth floor of the building has its own specialism: selling second hand iPhones from Europe and the US. Many of the phones sold here are legitimate trade-ins, returned by western consumers to network operators or phone...