expression, noun
A straightforward phrase meaning a habit that is undesirable or harmful. Often used in self-reflection or gentle criticism.
爪を噛むのは悪い癖だ。
Biting your nails is a bad habit.
彼は遅刻する悪い癖がある。
He has a bad habit of being late.
癖 is a general term for a habit or tendency, which can be neutral or negative. 悪い癖 explicitly marks the habit as bad.
習慣 is a more formal word for a custom or routine practice, not necessarily negative. 悪い癖 is more colloquial and personal.
Compound of 悪い (bad) and 癖 (habit). The phrase is transparent and follows standard adjective-noun modification.