Rarely have I received pingbacks, except my own. In the past week I received one from an inactive blog, and one from a 2008 blog. In my opinion, neither had much relevance to what I posted. Do you know if this is related to the automatically generated similar posts by WordPress at the end of my blog post that I never see (but other viewers do see)? Is this something of concern, or should I just continue to ignore an delete them? How does this happen? Thank you.
Pingbacks occur when another site links to content in your site. http://en.support.wordpress.com/pingbacks/
If you do not find any value in the site that’s linking to yours, and/or is it appears to be a splog (spam blog) or has links to bad neighborhood sites, and/or if you do not believe that posting the pingback will result in sending your readers to another high quality site then delete the pingback.