What are three factors that could contribute to a source not being credible?

The three factors that could contribute to a source not being credible is it ineptness, unreliable and unattractive which are the opposed characteristics to what makes a source credibly valid and reliable or trustworthy. The supposed characteristics can make the source invalid as simple as having to read, comprehend and understand what it’s trying to say. In research or formal study many authors are very direct to the point and persuasively convincing in support to their results and outcomes. In addition, there are other co-authors that can support such claims and suggestions.