What does "hanging up a sheep's head but selling dog meat" mean?

"Hanging up a sheep's head but selling dog meat" is often used as a metaphor for using a good name as a signboard while actually peddling inferior goods; it means "outward appearance differing from inner reality, cunning and deceitful." Now let us take a further look at the allusion and usage of "hanging up a sheep's head but selling dog meat"!

The allusion behind "hanging up a sheep's head but selling dog meat"

Duke Ling liked women who dressed in men's clothing. The women of the whole state all wore such attire. The duke sent officials to prohibit it, saying: "If a woman dresses in men's clothing, tear her clothes and cut her sash." Though clothes were torn and sashes cut, it could not be stopped. Yan Zi had an audience with the duke, and the duke asked: "I sent officials to prohibit women from dressing in men's clothing, tearing their clothes and cutting their sashes, yet it still does not stop. Why is this?" Yan Zi replied: "You have them wear such attire within the palace, yet prohibit it outside; it is like hanging up an ox's head at the gate while selling horse meat inside. Why do you not forbid it within the palace? Then no one outside would dare to do it." The duke said: "Excellent." He ordered that women within the palace not wear men's clothing, and before a month had passed, no woman in the state wore such attire.

Translation of "hanging up a sheep's head but selling dog meat"

Duke Ling of Qi liked women to dress in men's clothing, and all the women of the state wore men's clothing. Duke Ling sent officials to prohibit them, and pointed out: "For a woman who dresses in men's clothing, tear her clothes and cut her sash." Although people all saw that some had their clothes torn and sashes cut, it still could not be prohibited. When Yan Zi came to have an audience, Duke Ling asked: "I sent officials to prohibit women from dressing in men's clothing, tearing their clothes and cutting their sashes, and it was all seen with my own eyes, yet it still cannot be stopped. Why is this?" Yan Zi replied: "You let the women within the palace dress in men's clothing, yet prohibit it outside the palace; it is just like hanging up an ox's head at the gate while selling horse meat inside. Why do you not make the women within the palace not dress in men's clothing? Then no one outside would dare to either." Duke Ling said: "Good." He ordered that women within the palace not dress in men's clothing, and after a month had passed, no woman in the whole state dressed in men's clothing.

Usage of "hanging up a sheep's head but selling dog meat"

1. This is an educational bookstore, but what it sells inside is all pirated novels; it is simply hanging up a sheep's head but selling dog meat!

2. Nowadays some merchants are purely hanging up a sheep's head but selling dog meat; their advertisements are louder than anything else.

3. The diehards in China today are exactly like this. The constitutional government on their lips is nothing but "hanging up a sheep's head but selling dog meat." (Mao Zedong, "The Constitutional Government of New Democracy")