1. A computer-implemented method for spam detection in a collection of multimedia items, comprising: storing the collection of multimedia items in a memory of a computer system, each multimedia item including a description of the item, the description including a plurality of tokens; and for at least one multimedia item: selecting a plurality of portions of the description of the item and for each selected portion counting a total number of unique tokens in the selected portion, wherein unique tokens appearing more than once in the selected portion are counted only once; determining a distribution of unique tokens for the multimedia item using the total number of unique tokens in each selected portion of the multimedia item; and responsive to the distribution of unique tokens exceeding a distribution threshold, marking the multimedia item for a future spam filtering action.