Self righteousness is usually something that creeps up on us.  It occurs when we believe that we deserve something ... maybe just respect.  But self righteousness is a dangerous tool.  It usually leads to pride, causes us to not really love others and most of all - it prevents us from learning anything from God.
Self righteousness comes about when I am focused on how right I am (or how wrong you are).  But it is blinding.  How right I am is rarely the point.