A system for classifying documents in a collection of documents according to their intended readerships includes: a computer configured to select a document in the collection of documents; and a computer to determine a characteristic of the selected document, the characteristic being: misleading when the document includes one or more features that are determined to be for a purpose other than reading the document; commercial when the document includes features that are presented for a commercial purpose; or personal when the document includes features of a personal opinion. A computer classifies the selected document as misleading, commercial, or personal according to its determined characteristic; and a computer repeats the steps of select document, determines a characteristic of the selected document, and classifies the selected document for additional documents in the collection. At least some documents are classified as misleading, some as commercial, and at least some as personal.