"Maintain high standards of ethics and professionalism: Mentors and mentees must strive to uphold appropriate ethical behavior as professionals." 

Best practices for ethics and professionalism in a mentoring realtionship:

• Promote mutual respect and trust
• Maintain confidentiality
• Be diligent in providing knowledge, wisdom, and developmental support
• Carefully frame advice and feedback so it is well-received and constructive

From Amy Greil's "A Story of Mentoring" found online at http://www.kenoshanews.com/news/amy_greil_a_story_of_mentoring_493097750.php

Honesty is essential in any mentoring relationship. If you disagree with your mentoring partners opinions, let him or her know in a respectful manner.