Disqus comments fails to load on localhost?

you should set this to make it work:

var disqus_developer = 1; // this would set it to developer mode

Reference: http://ray247.wordpress.com/2009/09/02/how-to-develop-with-disqus-on-localhost/

None of the solutions above worked for me as of September 2013.

To get it to work I had to add localhost to the "Trusted Domains" list on this page:

http://[disqus_shortname].disqus.com/admin/settings/advanced/

and also use the "Universal Code" found below to embed it into my blog posts:

http://[disqus_shortname].disqus.com/admin/settings/universalcode/

And it works! :)