Generally, people like to be amused. So many people I know follow sites like FML or FailBlog, which essentially capture humor in unintentionally funny situations. My blog is along the same lines, except finding humor in mistakes made in written language.
I don't think people are going to question my credibility because it's not really something that requires it. But if, by chance, they were to question "How can I trust that you're picking out true errors?", I do have it in my About Me that I'm attending URI for a Writing & Rhetoric degree. This can maybe coax the reader into excepting my role as an "editor" in the blog since I am being educated on the subject of written language.