雞鳴狗盜

Etymology
From the story of  escaping from King Zhao of Qin  with the help of his two retainers, one crowing like a chicken and the other disguising as a dog to sneak into the Qin palace to steal a white fur coat for the king's concubine:

Idiom

 * 1) lowly skills; skills of little worth
 * 2) people with lowly skills
 * 3) base and despicable