Answer: Help your boss see the problem by getting his attention without insulting his ability. Start by viewing things from his perspective. Friend or not, this woman was his choice for a high-level job. So when you say, “She has no qualifications,” you’re really saying, “You were an idiot to hire someone like that.” Not exactly the smartest approach. You need to:
* Convey the gravity of the situation by focusing on the facts that matter most to your boss. His reaction to "she treats everyone rudely" may be that you should have thicker skin.
* Show that her “costly mistakes” increase expenses or alienate customers. Then he might start to worry.
* Present a business case that reflects concern for the company, not personal animosity. Do so in a calm, professional manner. Anything that resembles whining or complaining will turn off your boss.
* Don’t expect him to admit to a hiring error or agree that she’s a problem. If he simply listens to your concerns, then he’s starting to get the message.
Caution: If the quote marks around “good friend” mean that she's more than just a buddy, you may be out of luck. People are seldom rational about their romantic partners.