溢美之词

Comes from 《庄子·人间世》 (Zhuangzi, 'In the Human World'): 'when two parties are both pleased, their words inevitably overflow into excessive praise; when both are angry, into excessive blame.' 溢 ('to overflow') is the key image: praise that has spilled past truth.

Often self-deprecating: a humble Chinese speaker, when complimented, will respond 这是溢美之词 ('that's just inflated praise') to deflect the compliment. Also used critically of biased reviews or overhyped book blurbs.