A study by researchers in Cornell university in 1999 found that idiots overestimate their abilities, and the good guys underestimate them. Also, the idiots fail to recognize good qualities in others. From the wikipedia
- incompetent individuals tend to overestimate their own level of skill,
- incompetent individuals fail to recognize genuine skill in others,
- incompetent individuals fail to recognize the extremity of their inadequacy,
- if they can be trained to substantially improve their own skill level, these individuals can recognize and acknowledge their own previous lack of skill.
See full article. It is left as an exercise to the motivated reader to figure out what this means if a manager is incompetent (e.g. in terms of hiring).