"propaganda" is not necessarily media that is trying to "cover up some truth."

From wikipedia:

Propaganda is a form of communication that is aimed at influencing the attitude of a community toward some cause or position by presenting only one side of an argument. Propaganda is usually repeated and dispersed over a wide variety of media in order to create the chosen result in audience attitudes.

As opposed to impartially providing information, propaganda, in its most basic sense, presents information primarily to influence an audience. Propaganda often presents facts selectively (thus possibly lying by omission) to encourage a particular synthesis, or uses loaded messages to produce an emotional rather than rational response to the information presented. The desired result is a change of the attitude toward the subject in the target audience to further a political agenda. Propaganda can be used as a form of political warfare.

While the term propaganda has justifiably acquired a strongly negative connotation by association with its most manipulative and jingoistic examples (e.g. Nazi Propaganda used to justify the Holocaust), propaganda in its original sense was neutral, and could refer to uses that were generally benign or innocuous, such as public health recommendations, signs encouraging citizens to participate in a census or election, or messages encouraging persons to report crimes to the police, among others.