The cleaner your blog the better. Most readers have a short attention span and they do not want to get distracted by unnecessary or non-relevant information. Despite that fact many bloggers forget to remove such extra data from their sidebars or from the blog posts. Below you will find some examples of unnecessary information:
Author information: Unless your blog has more than one author it makes no sense to display “Written by John Doe” after every single post. Readers that want more information about the author can visit the “About” page.
Meta data: Most WordPress themes come with a meta section on the sidebar where you can find admin links like “Login” or “XHTML Valid”. While this information might be useful for the blog owner it offers no value for the reader.
Recent Comments: The blogs that have a “Recent Comments” section usually display only the name of the person that posted it and the first two words of the comment. Readers interested in following the comments of a particular post will probably click on that post directly and not on the “Recent Comments”.
Calendar: Unless you write about time-bound content there is no reason to have a calendar on the sidebar of your blog. People blogging about a journey or a conference, for instance, should use the calendar because it enables readers to track the evolution of the event. If your blog is not in that situation, however, ditch the calendar.
Badges: Some blog directories or networks require the members to place a badge on their sites. Most of the times, however, those directories send very little traffic while creating a lot of visual pollution. Be careful to evaluate the real benefits before cluttering your blog with dozens of badges.
Overall make sure that all the elements on your blog are creating value and not just detracting from the user experience. If you are not sure about what adds value and what might disturb the readers you can ask them or use services that track where they are clicking around your blog. Do you have any other examples of unnecessary information on blogs?