It is very obvious that GDO is receiving as much spam as real content. Especially by certain people believe that SEO is all about posting links on irrelevant sites.
Causing many issues created on GDO just for spam removal
For example the last 5 replies in a thread that I have subscribed to, are all spam, with a comment where the author tries to make it look like a relevant post, with no real content and a link to an irrelevant site
Most of these users create accounts just for the purpose of posting these links on GDO.
I would not mind someone trying to do some promotion in the name of commenting , with "Templatic" replies like "Congratulation for the great post"..but many users will have no option but to unsubscribe to their posts.
A proposed solution for this could be one or a combination of one or more of the below:
1) Allowing a user to post replies or create topics only after a certain period after registration
2) Restricting the new users to use a "Plain Text" Input format which does not turn Web page addresses and e-mail addresses into links automatically. The ability to use "Filtered HTML" Input format will be automatically granted to the user only after certain period after registration.
3) A more easier way to report (A "flag as spam" link below each comment). There could be some rule like "If a comment is marked as spam by more than 5 users, it is unpublished automatically."
Spammers have less patience and hardly mind to read forum/group rules to be aware of the above restrictions (or any) in place. If a spammer fails to post a link in a site, he hardly returns to the site for another attempt. For the more intelligent ones, there is always the issue queue at http://drupal.org/project/issues/groupsdrupalorg