肮脏(āng zāng) - filthy, dirty in Mandarin

肮脏 (āng zāng) is strong dirt. Not a bit dusty, not in need of a wipe, but genuinely filthy: a blocked drain, a hand covered in oil, water you would not touch.

It carries the moral sense too, exactly as English filthy does. 肮脏的交易 is a dirty deal and 肮脏的手段 are underhand methods. That second life is why the word turns up so often in journalism and in film dialogue.

The trap is reaching for it when 脏 (zāng) on its own would do. 脏 is the everyday word: 你的鞋脏了 means your shoes have got dirty, and nobody is offended. Calling somebody's kitchen 肮脏 is a judgement, not an observation. Note also that 脏 has a second reading, zàng, meaning an internal organ, as in 心脏 (heart).