The phrase "dost bang-up job" implies that someone has done an excellent job. However, if we were to look for antonyms of it, we would most likely come across words like sloppy, lazy, incompetent, or subpar. These words imply a lack of effort, care, or skill, and denote a job that is below average or inadequate. Other antonyms might be words that express a sense of disappointment or discontent, like disappointing, unacceptable, or unsatisfactory. It is important to note that using antonyms for "dost bang-up job" should be used with caution, as they can easily come across as negative or derogatory towards the person who did the work.