I guess that for ENTJs we have to learn that not everyone enjoys the competition since Fe is our weakest function, it just doesn't come naturally. We especially don't understand it in the arenas of sports or business since this is naturally a competitive undertaking in the first place.
I've never gone out of my way to sabotage somenone's effort. I am always doing what's best for the company and will bend over backwards to give everything to the team no matter how it may hurt me in the end. I learned from my ENTJ dad to take the job no one else wants so that they feel good about not having the worst job and they respect you as a leader for doing what no one else wanted to do. I am never purposely trying to hurt anyone. I've learned that the best results come from happy co-workers.
Now, I have been known to play devil's advocate in an argument simply to expand and strengthen my own point of view or to see how researched and/or logical the other persons point of view really is. It took me a long time to reazlize that most people see a challenge to their opinion as an act of war, or my arguing as pointless. For an ENTJ it is merely an act of clarification or figuring out the soundness of an idea.
I've had to train myself to recognize the signs that I'm offending people. The truth is that we ENTJs so rarely get offended (I've told people that they actually have to be blunt and call me an asshole if they want to be offensive, but in the end I'm usually so busy analyzing why they might be feeling angry that I still don't take it personally.)
I also feel that if someone is in a leadership position they should not take it personally if an employee sees a problem and has a practical solution. I find it interesting that when there has been unfair leadership and the co-workers needed a champion they are quick to jump behind my back and let me take the brunt of the blows, because once again, I'm not afraid of challenging the powers that be if it means solving a problem that every one else is too chicken to confront.