I've had great mentors in my life. I've also experienced my fair share of toxic mentors, what Howard Gardner in his book Five Minds for the Future, refers to as "antimentors" or "tormentors".
I learned from my toxic mentors the importance of setting clear (and reasonable) expectations upfront. I also became skillful in negotiating my way out of toxic relationships without burning bridges. More importantly, I learned to establish healthy boundaries for myself.
Interesting, you don't hear or read as much about toxic mentors, but they're out there and you need to recognize five warning signs that your mentoring relationship could be heading south.
Your mentor chastises you publicly with the excuse "I'm toughening you up--that's how we do it around here."
Mentors are worth their weight in gold when they bring to your attention behaviors that might not be working for you, but not in public.
What if your mentor's behavior publicly embarrasses you and he doesn't recognize it? Pointing out your mentor's blind spots in a way that doesn't burn a bridge can be a tough conversation to have with someone you admire. However, learning to negotiate your boundaries is a valuable skill to have in your toolbox.