Here’s an official video from Google discussing comment spam and forum spam.
If you own a WordPress site, you know there are bots designed to post fake comments on your site.
DON’T APPROVE THEM.
Because if you do, Google will penalize your sites.
Make sure you use a plugin such as Akismet to stop comment spam.
If you run a forum, make sure you use a special captcha that can not be cracked by Spam programs such as UNO or SE Nuke.