Vote stuffing used to be a big problem in AniDB. Ratings used to be just the averages of all the votes, making it easy for narrowminded people to register multiple accounts in order to bump a series rating. This happened especially in the so called Top 10, each series there used to have several hundred votes of both 1s and 10s, from fanboys of different shows.
Salvation has arrived! A heuristic was deviced which virtually nips this problem in its bud. It no longer matters. Votes are weighted in a manner that makes vote stuffing obsolete.