tarnish

By this time a series of scandals had severely tarnished the candidate's image/reputation.

到这时，一连串的丑闻已使这名候选人的形象／名誉大大受损。

The silver necklace began to tarnish after being exposed to air for too long.

这条银项链在暴露于空气太久后开始失去光泽。