There is another factor which greatly affects the rep score of a node.
Has the root node been frontpaged?
Once a node reaches the Monastery Gates, the score gets greatly increased. This also has the same effect on the replies to the root node. The distribution of 'High rep' becomes skewed by dint of its mere presence on the front page - just because it's high rep does not necessarily imply good work.
For those who don't know, frontpaging is something that any friar or above can do, if they think that a node is of sufficient quality or interest. Also note: you cannot frontpage your own nodes.