Wuxia heroes tend to get themselves into trouble in various ways. Kiu Fung was too brash and often hurt or killed people without necessarily intending to. Gwok Jing wasn't particularly bright and often bungled into danger. Yeung Gor's hot temper got him into trouble from time to time. Cheung Mo Gei's Achilles' Heel was beautiful women.
Deun Yu's problem, at least in DGSD '81, seemed to be that he could not control his laughter.
1. Laughing at Yu Gwong Ho when Yu dropped the wallet that his fiancee' had given him got Deun Yu into trouble with the Mo Leung Sword Sect.
2. Later, while spying on Yu Gwong Ho and his fiancee, Deun Yu laughed at the mushy exchange the couple was sharing and was discovered (this worked to his advantage, however, because it led to his discovery of Lee Chou Sui's cave).
3. While visiting Man Sau Manor to tell Gum Bo Bo about Chung Ling becoming the prisoner of the Divine Dragon Union, his laughter gave him away to an irate Chung Man Sau.
Deun Yu seemed to get into an inordinate amount of trouble because he couldn't stifle his laughter.