noun
Often used in the phrase 難癖をつける (to find fault with, to pick on). Refers to a perceived shortcoming or a pretext for criticism.
彼はいつも私の仕事に難癖をつける。
He always finds fault with my work.
その批評家は小さな難癖を探してばかりいる。
That critic is always looking for minor flaws.
Compound of 難 (difficulty, fault) and 癖 (habit, peculiarity). The combination suggests a habitual or persistent fault.