They say Wu Dalang loves to play night owl, and everyone has their own bird to walk.
The reason why Fourth Wu could make it into the Capital's eight oddities was not due to his two specialties, but rather the unique skill he developed from those specialties.
As a renowned friend of women in the Capital Circle, Fourth Wu knew the ins and outs of the ladies of high society like the back of his hand. Even if he hadn't visited them personally, which of his well-connected acquaintances wasn't privy to the choicest tidbits and a lover of gossip?
Thus, whenever it came to matters concerning the inner courtyard, what came out of his mouth, if not entirely truthful, was never far from the truth.
If he said that a certain lady was having an affair, or that she led a dissolute private life, then it definitely was true. Even if the family in question denied it at the time, the truth would eventually come out.