狗咬吕洞宾，不识好人心

狗咬吕洞宾，不识好人心

Literally means:

the dog snarls and snaps at Lǚ Dong Bin and doesn't recognize his kindness

Actually means:

mistake a good man for a bad one

吕洞宾, one of the Eight Immortals in Chinese ancient myth. One man named 苟杳 (taking the same pronunciation as 狗咬, meaning dog biting) was good friend of 吕洞宾, and they both mischievously helped each other the ignorance of one another and thus caused misunderstanding between them. Based on this story, people coined the idiom 苟杳吕洞宾，不识好人心. Later, for the convenience of reading, it was changed into 狗咬吕洞宾，不识好人心.

This phrase figuratively means one cannot distinguish the good from the bad and mistake other's good will. It is usually used as a complaint. Derogatory.

吕洞宾，传说中的八仙之一。有个苟杳（读音同“狗咬”）和吕洞宾是好朋友，他们曾经用恶作剧的方式暗中帮助过对方，并因此一时引起了误会。于是人们把他们故事叫做“苟杳吕洞宾，不识好人心”。后来为了便于认读，人们把句子改成了“狗咬吕洞宾，不识好人心”。

狗咬吕洞宾，不识好人心，比喻分不清好坏，误会了别人的好意。常用来表示埋怨。具有贬义色彩。