The audiences of generalist television's newscasts reflect that the viewers' interests and loyalties are constantly changing. Research shows that several elements influence the success of programs and formats, but in this paper, we draw attention to the factors that determine the credibility of newscasts. We also want to know how pluralism is safeguarded in newscasts, as we consider that credibility and pluralism are two intertwined values that influence one another. As credibility is a subjective value, it is required to find new information criteria that is suitable and of the utmost rigor. The main aim is to delve into whether there is a consensus on the basic parameters for the definition, identification, and assessment of credibility of nationwide public service media in Spain. Moreover, we are also interested in whether audience figures can be used to determine the degree of trust of newscasts. The analysis brings forward the observations of researchers, scholars and media professionals that offer a vision on the different approaches that integrate the multiple aspects affecting news consumption and interpretation. We conclude that credibility is a concept composed of multidimensional components, resulting from a process where different filters condition fact perception. That is why a story can have different meanings, related to the different point of views of citizens.