Spam is the abuse of electronic messaging systems (including most broadcast media, digital delivery systems) to send unsolicited bulk messages indiscriminately.
Blog spam, or comment spam is spamming on weblogs. In 2003, this type of spam took advantage of the open nature of comments in the blogging software Movable Type by repeatedly placing comments to various blog posts that provided nothing more than a link to the spammer’s commercial web site.Similar attacks are often performed against wikis and guestbooks, both of which accept user contributions.

If you run a blog that’s been around for any reasonable length of time, whether it has high or low traffic, no doubt you’ve experienced or you’re beginning to experience the frustration of dealing with blog spam – comments and trackbacks submitted automatically by seedy individuals looking to peddle their wares or misinformed marketers and site owners looking for a quick fix to their traffic and ranking woes.

How do comment spammers find your blog?
Simply having a blog with a linkable web address is reason enough for most comment spammers. It is just a fact in having a web presence. Most of the comment spam coming to a blog originates from robots.
Spammers look for your site in hopes of establishing links back to their website. This is one of the most important aspects of search engine optimization. The more sites have links from other sites back to their site is viewed as a good thing, especially if the content, keywords and dialogue are relevant. And the more page rank you have the more you are susceptible to comment spam.
If you have a page saying, “leave a comment” or have a “do-follow blog”, you have an open invitation for comment spam.

Link Builders Perspective
Blog commenting is quickly becoming more and more popular as a way to build links back to your website. So the link builder comes along, looking to build links to a site on computer financing. They find this perfectly relevant post by another blogger about computer financing, so they take some time, read the article, write a well thought out comment, and clicks submit.
There are three things that happen at this point. They are greeted with their comment being posted (rare, but it still happens), their comment is posted but with the friendly “your comment is in moderation” at the beginning, or the infamous white screen of death – similar to the blue screen, but this one likely means that the comment has just went into the Akismet spam folder, never to be seen by human eyes again. The comments in moderation sometimes get approved, but most of the time not. Why? Because the blog owner considers them a spammer.
Prove You’re Not a Spammer
So what should link builders do to prove they are not spammers and want to leave quality comments?
1. Leave quality comments.
This should be pretty obvious, but leave quality comments. Read the article, write a good response. Your response can be directed not only to the blog author, but also to other commenters on that post.
2. Get a Gravatar.
Associate the email address you use when commenting with a photo (preferably of a real person, not a logo or other image). Comments with photos are more likely to get approved since they can be associated with a real person instead of a bot, spam, or software.
3. Follow the rules.
Take notice of other comments on the site. Do they use keywords or real names? Does the site use KeywordLuv? Is there a comment policy? See what kinds of comments get approved, and what format they are in – make sure yours follow the same pattern, and they are more likely to get approved.
4. Don’t participate in “one night stand” commenting.
Sure, you want to drop your link on a post with high PageRank that is relevant to your topic. But why not also pick one other article on the site and comment on it to. This shows the blog author you care about more than just getting your link on a specific page.
5. Don’t participate in “drive by” commenting.
Sure, you want to drop your link on several articles on one blog. One or two, maybe three articles at a time isn’t so bad. But don’t go spraying comments on ten to twelve articles in one go. Most commenters who do this are in a rush and forget that comments are time stamped. If a blog owner sees that you left ten comments in the span of ten minutes, they know you didn’t take the time to read the article.
6. Contact the blog owner.
What will make your comment stand out from the crowd? If you see it goes into moderation, or you know that you are on the Akismet spam filter, take an extra moment to contact the blog owner through their contact form or email. Let them know that you read their post, submitted a comment, but fear that it might be lost in the spam folder. This will tell the blog owner you are taking more than just two seconds to drop a link and run.
7. Go above and beyond.
Have a Twitter account? Tweet the post, including an @reply to the blog owner. Chances are, seeing your name outside of their site will further stress the point that you are not just a comment spammer, but a real person interested in their site.

spammer

There are many WordPress plugins that help but the task remains; You must monitor for comment spammers. Commonly used plugins include:
1. Akismet – This is the most known and is a trusted comment spam fighting plugin. It helps in keeping the spam comments isolated. Make sure that you delete spam comments regularly.
2. WP-SpamFree –I learned about this plugin and installed it early on. It only helps monitor comment spam and the deletion task remains, but it is useful.
3. Optimize DB – This plugin runs an “optimize table” command to keep the WordPress database clean.

Sources:

http://en.wikipedia.org/

http://kikolani.com/

http://www.jerryrlucado.com/

Photo sources:

www.directsaleswebmarketing.com/

fromthe2one5ive.wordpress.com/

blog.rayboy.org/