What does "gentle scum" mean?

On the surface, he is knowledgeable, but in fact, he is full of something.

Gentle scum

Pronunciation: [s and wé n bà i lè i]

Quote: Liu Qinglin's Beyond the Mountain Village: As the saying goes, gentle scum, this product is a typical one.

Chinese character strokes:

Synonym of extended information: the devil wears Prada

Pronunciation: [y and gu ā n q í n shòu]

Interpretation: tidy appearance, like people, but like animals. Metaphor is a despicable person.

Source: Ming Lingmengchu's "Two Moments of Surprise": "Not only devil wears prada; It is a jackal among animals. "

Vernacular translation: not only animals in clothes, but also jackals among animals.

Grammar: formal; Become an object; Point to bad offspring.