Regarding the information on the Four Great Bandits, it wasn't much mentioned in Yin Bukui's strategy guide, to the extent that it only had the collective name "Four Great Bandits." Even the actual names had been written by Yin Bukui as "can't remember clearly," which shows how trivial their part in the original story was.
Ye Weiming and Youyou only got a preliminary concept of the existence of these "Four Great Bandits" through the narration of Master Lu.
A blade of grass doesn't grow under Toward the Heavens;
Not a chicken or dog is left alive at Fang Jinding's hands;
Scorched earth for thousands of miles chasing Mao Zao;
Ghosts weep and gods wail at Cao Yinglong!
Just by listening to this doggerel that included the names of the "Four Great Bandits," one could tell how cruel and terrifying this group was.