Comment on Comments WordPress SEO Plugin by SEO Dave.
Basically I’d not checked the comment id was always to an approved comment.
Have made a fix for the Stallion Responsive theme version (similar code to the plugin is built into the SEO theme I develop and it has the same bug) which I’ll put an update out to after testing the fix on some of my popular sites (few days probably).
Wasn’t hard to fix in the theme (running the fix here now), so shouldn’t take long to update the free plugin as well (slightly different code, far less features, but same principal).
When fixed (like on this site) if an SEO comment URL is loaded which isn’t an approved comment like : https://stallion-theme.co.uk/wordpress-seo-comments-plugin/?cid=99999
It will load the main post only and add a canonical URL to that post in the code: that means if your users access the URLs or Google indexes them they won’t see pending/spam/trash comments and medium term if Google had indexed them any SEO benefit will be redirected back to the main post.
Thanks for letting me know.