You have an overwhelming, visceral, adverse reaction.  First, step back and examine what it is that is pushing your hot buttons.  If intentional, your opponent has a tool that can be used to your detriment and his or her benefit.  If unintentional, your reaction can stand in the way of positive negotiations.  Either way, the phenomena will negatively impact your ability to do your job.  Losing control is never in your or your client’s best interest.  Get back on track.  Deal with it.