When Pau But Tung first met Deun Yu, Pau was quite rude to the youth. Then again, Pau is rude to pretty much everybody (except Mo Yung F'uk). With Pau, you have to win his respect (usually by outfighting him, like Kiu Fung did).
Did Pau But Tung really dislike Deun Yu and thus treat him rudely, or was being rude just Pau's perverse way of being "friendly?"