Team Poison: Hating Correction
I can think of nothing more poisonous to a team dynamic than the attitude that hates correction. Prideful teammates that cannot receive feedback in a healthy way always become a thorn in the sides of their teammates. As time goes on, the teammates of a prideful individual begin to lose hope that any improvement is possible. That person begins to be worked around and that distance causes a lot of extra work for everyone. The unhealthy team dynamic begins to become a burden the team must carry when it should be an engine that carries the team.