Quark on coming to the duel says, "I am Quark, son of Keldar and I am come to answer the challenge of D'Ghor, son of... whatever." Quark probably really didn't know D'Ghor's father, but to a Klingon noble it's a pretty cutting insult. His use of "whatever" instead of "whoever" is also a very subtle use of "It" Is Dehumanizing. In response, D'Ghor shoots an outraged glance at Gowron, showing that, whether intentional or not, the Trash Talk hit its mark.
