FACT: Abusing comment fields of innocent sites is a bad and risky way of getting links to your site. If you choose to do so, you are tarnishing other people's hard work and lowering the quality of the web, transforming a potentially good resource of additional information into a list of nonsense keywords.
FACT: Comment spammers are often trying to improve their site's organic search ranking by creating dubious inbound links to their site. Google has an understanding of the link graph of the web, and has algorithmic ways of discovering those alterations and tackling them. At best, a link spammer might spend hours doing spammy linkdrops which would count for little or nothing because Google is pretty good at devaluing these types of links. Think of all the more productive things one could do with that time and energy that would provide much more value for one's site in the long run.
What can I do to avoid spam on my site?
Comments can be a really good source of information and an efficient way of engaging a site's users in discussions. This valuable content should not be replaced by gibberish nonsense keywords and links. For this reason there are many ways of securing your application and disincentivizing spammers.
- Disallow anonymous posting.
- Use CAPTCHAs and other methods to prevent automated comment spamming.
- Turn on comment moderation.
- Use the "nofollow" attribute for links in the comment field.
- Disallow hyperlinks in comments.
- Block comment pages using robots.txt or meta tags.