there was one other thing they may have forgot to mention above, but I recall another site where users posting renders would complain if they got low ratings, and ask the admin to delete any low ratings.  I dunno if this applies to this gallery, but in the other gallery the reason they complained was that they might be considered as candidates for a pay gallery if somebody, possibly their peers, judged them to be excellent.  there's no pay gallery here AFAIK, but there may be some other process where lots of positive comments and high ratings are useful in some material way.