He may be plain-looking, but his talent is outstanding.
Tips
history
Rooted in 《左传·昭公二十八年》, where a father, warned that his son was plain-faced and unlikely to impress, said "if you had not spoken, I would nearly have lost my son." The Tang statesman Pei Du later used 尔貌不扬 of himself in self-deprecation.
usage
Classic setup for a "but" clause - 其貌不扬，却…… ("plain-looking, yet..."). Almost always a lead-in to hidden merit.
