User blog comment:DancePowderer/719 Prediction/@comment-3177613-20130825163545/@comment-1595565-20130825180619

Well, Whitebeard may have been more famous, but the yonko we knew at the time (and even now) all seemed a bit reclusive, so it's understandable that people wouldn't know their abilities too well; hence Sengoku's surprise upon learning that all their scout ships had vanished. Luffy has had multiple newspaper articles written on him both before and after his big reappearance on Sabaody. Also, based on the rumor's about Luffy that were mentioned in the locker room several chapters ago, I think Doflamingo has made the Dressrosa public aware (if only somewhat) of what Luffy can do. At the very least, someone in the audience is going to recognize him after his Hawk Rifle attack.