It crops up occasionally that people want to leave a comment with a reference to a Google webpage or a Google search result.
Unfortunately on a daily basis my server is hit with comment spam with links pointing to Google redirects, or Google subdomains.
Here are some examples:-
Due to all the spam, Google.com ends up on my domain blacklist, and a single URL occurrence will still allow it to be visible within my standard settings for comment moderation, as long there are no other specific penalties imposed by Spam Karma.
Multiple occurrences will end up buried amongst the spam, which is not something I wade through on an hourly basis.
Google.com isn’t the only domain with such a penalty, for instance it is also the case with tinyurl, blogspot and many more.
I don’t moderate comments because someone disagrees with me, I do however delete comments that clearly suggest that they were written just to get a link, in fact especially when I suspect the sincerity of comments such as “Great Post”.
Spam Karma has its flaws, but is also not subject to the collective intelligence of Akismet.
I know Google Groups spam is something dear to Igor’s heart, so I should mention his Project Honeypot Spam Domains List