In general, the more passively you've acquire information through media, the less value it will have to you, and the less it can be trusted to be free of intent to manipulate your behavior.
We can evaluate passivity and usefulness both in terms of comparing propositions, and comparing various media. For example: say running in salt water cures plantar fasciitis, a painful condition of the tissues on the bottom of the foot that afflicts runners. This would be fantastic, since it would be cheap and easy to do. But no one can make money from such a cure, so there would be no commercials for it, no campaigns, no radio spots. You would have to learn this by looking it up online or digging through running magazines. The key is to think of incentives; a running magazine will make you like them more and buy more issues if they bring you information like that.
There is a difference in passivity of information absorption between various media. It costs money and effort to disseminate information through mass media (especially TV and radio; i.e., those which have a fixed number of outlets, and which by their nature require little effort to absorb.) These passive media are asymmetric, so the information-senders are not especially likely to have utility functions that are closely aligned with information-consumers. That is to say, the information senders are most likely to expend that money and effort only when they believe they're getting something in return, which is not necessarily anything that the information consumers are interested in providing them.
Usually, that's money (from advertising or from a product purchase), but sometimes it can be political power, as in propaganda or political campaigns. In addition, if people have irrational beliefs about the future value of their spreading information (e.g. from religion), that may also cause them to go to great lengths in the same way, although this only occurs a minority of the time.
In some cases, TV and radio companies and stakeholders have information that they do not want information-consumers to have; that is, disseminating this kind of information has negative utility, because this information often lets the information-consumers make more rationally self-interested decisions about how to weight the information they're receiving. This is why investigative journalism exists.
Print is the least passive medium and books are not aggressively marketed, so on a per-hour basis of books consuming one's attention (vs. televsion or radio), we would guess that the end consumer is benefiting more from the content. Books are typically not great vehicles to sell products (other than themselves); there are few commercials in books. Since there are now applications that passably turn print into (more passive) audio, one prediction is that books will begin to be released automatically with sound file versions (or intended only as sound files), and that the information in these books will be on average less valuable to consumers.
This principle does not necessarily hold with acquaintances who bring information (passively) to your attention, because their utility function is more likely to align with yours. You can trust a restaurant tip from a friend who likes you and wants you to be happy, more than a television commercial for that restaurant.