In evaluating a source, it is important to consider how you will use the source. Is it for an academic paper? Are you trying to learn more about an issue? Do you want to have information to persuade someone?
Most sources are not inherently "good" or "bad," but some sources are more appropriate than others in a given situation. For instance, you should cite scholarly articles for academic papers, but a popular source, like a newspaper, might be more useful to convince a friend or relative.