How do I determine which backlinks are bad?

A year ago, my site was ranked on the first page for nearly every search term. Now, I have dropped way,way back. I have rebuilt my site to make it Pand/Penguin friendly but still have no improvement. I feel that bad backlinks may be the culprit. From the reports that I have run, I have over 40,000 back links to my web design site. How can I determine which ones Google doesn't like…and, is there an easy way to get them removed other than manually through Google Webmaster Tools?

See original post by salai