When Brazilian K-pop fan Tami spotted a social media post last month selling a rare Polaroid photo signed by ZeroBaseOne member Zhang Hao, she jumped at the opportunity. The seller identified himself as a South Korean named Park Chae-ah, according to the Chosun Daily newspaper. She transferred the money. Then Park switched his account to private and vanished. Tami* is far from alone. Across Brazil, home to one of Latin America’s most passionate Korean pop culture communities, scammers have found...