Ever since Catfish appeared in the States earlier in the year, debate has been raging about its bona fides. On the face of it an ingenious documentary playing smartly with the potential and pitfalls of social networking and the nature of personal identity in the cyber age, the film has triggered cries of “foul” from a number of critics and viewers. Morgan Spurlock, who made the junk-food odyssey Super Size Me, has called Catfish “the best fake documentary I’ve ever seen”.