chuī máo qiú cī
lit. to blow apart the hairs upon a fur to discover any defect (idiom); fig. to be fastidious
nitpick
dà chún xiǎo cī
great despite minor blemishes
a rough diamond
zǎo gòu suǒ cī
to wash the dirt to find a defect (idiom); to find fault
to nitpick