In one embodiment, a method includes receiving a set of normalized attribute values that define a particular item being offered and a corresponding threshold score for each of the normalized attribute values. The method further includes, for each attribute value of a candidate item listing, determining a score for the attribute value based on whether it matches a corresponding normalized attribute value, and determining whether the score is above or below the corresponding threshold score for the normalized attribute value. The method still further includes determining whether the candidate item listing describes the particular item being offered based on a set of rules that define an acceptable number of scores that are allowed to be below the threshold scores.