The concept of a “bad egg” as a metaphor for a bad person is a fascinating point of cultural convergence between Chinese and English. However, the usage of 坏蛋 (huàidàn) is far more frequent and integrated into daily life in China than “bad egg” is in the West.
坏蛋 (huàidàn) is primarily an informal, conversational term. Its meaning is heavily dependent on the situation and the speaker's tone of voice.