A person who regularly waits for others to make a mistake and then points this out. The mistake vulture enjoys doing this.
As a vulture circles the creatures on the ground patiently waiting for one to fall, so the mistake vulture stands back until it is time to swoop. He will then step in and feast upon the tasty carrion that is pointing out another's error.
Mr Mistake Vulture: Dan I've been watching you and it seems you've made a mistake performing this particular task.
Dan Reeves: Sorry Boss... Thank You Boss... Whatever you say Boss...