1. A network device, comprising: a transceiver to send and receive data over a network; and a processor that is operative to perform actions, including: determining a plurality of document features for each document in a plurality of documents, wherein the plurality of documents include at least one document defined as having sufficient subject matter specificity, and at least one other document having insufficient subject matter specificity; training a classifier based at least on the plurality of document features; providing to the trained classifier, at least one other document, wherein the trained classifier determines a quality value for the at least one other document; and if the determined quality value of the at least one other document is above a quality threshold value, identifying the at least one other document to have sufficient subject matter specificity, and providing the at least one other document to a client device for display.