I've known some very nasty people in this profession. I'm very fortunate not to have anyone like that in my current department, but I've seen very bad situations in the past. Places where I dreaded going into the office.
Academic politics can be quite brutal; the competition to get a job at all can be quite fierce as well.
A good rule of thumb is that no conflict among colleagues should ever effect the graduate students. A graduate student should not have to worry about putting two colleagues together on the same committee or having to take sides in a faculty conflict.