Who was the toughest engineer you've ever had to work for? Why was it so tough to work for them and how did you adjust?
Never go negative on a former employer, boss or coworker when asked a question like this. It almost always backfires because the interviewer will be left wondering where the real problem was – with you or someone else. Always maintain a positive attitude when being asked questions that could be designed to uncover something negative about you, your experience, or the way you handle yourself. Instead, put a positive spin on your response and address how you've learned and adapted your work style to meet the needs of your employer.