Sometimes a film adaptation can be a paradox: the more faithful the adaptation, the less it works as cinema. The reverse is also true and so it goes with THE AMERICAN FRIEND. Although the spine of Patricia Highsmith's RIPLEY'S GAME is there (combined with elements from the previous novel in the series RIPLEY UNDERGROUND), Dennis Hopper's hyperactive, almost neurotic take on the role is miles away from the cold, sociopath described in the books. But next to PURPLE NOON, this…