What do you mean by scum?

The story goes like this: compare the useless things with the leftover medicine.

Once upon a time, there was an emperor.

One day, he visited the harem and found that all the concubines were sad and listless. The emperor was very anxious and immediately called the imperial doctor in the palace for treatment. A month passed, and somehow, the concubine's illness still didn't get better.

The emperor decided to send a list to the world and called the imperial doctor into the palace to treat the concubine. On this day, a man came to the palace and offered to treat this disease. Half a month passed and the emperor visited the harem again. I see the concubines are as charming as before. The emperor was overjoyed and decided to reward and entertain the magical doctor. When the emperor returned to the palace and passed by the harem, he suddenly saw many strange men lying at the entrance of the harem, all pale and emaciated. The emperor asked angrily, "Who is this?" The imperial doctor replied, "So is the residue left by the villain after taking medicine for the concubine!"