This topic came up on site-reference.com and it is a common topic for people looking to improve SEO. It is important to know about because if you’re running a fansite or fan fiction archive and wanting to learn SEO through link building, this method is probably one of the first one’s you’ll see.
Commenting on blogs can help increase your traffic in two ways: 1) Click throughs on your name or from links in your comment. 2) Search engines if the links are not rel=nofollow. For the second, the advice is that the more you comment on a diverse range of blogs, the more search engine juice you’ll get and the more visits from Google you’ll get. Bad SEO people encourage you to comment as much as possible where ever the links are rel=follow. What these bad SEO people fail to tell you is that doing so can actually hurt your SEO because you may end up on blacklist as a spammer. People report spam to services they use like akismet, disqus, etc. They develop their own internal blacklists. Your hard work commenting will go to waste as comments disappear. You risk worse for your site.
If you want to avoid the possibility of going into a black box because of your commenting, remember the following advice:
1. Read the article that you are responding to and respond accordingly. Title isn’t enough to demonstrate that. “This was interesting. I will read more of your blog.” is generally a sign that a comment is a spam comment and that you haven”t read the post. (If you want to say that, e-mail the author of the blog.)
2. Comment once in reply to a particular blog unless you’re willing to do a lot of number 1. Several comments of “This is fascinating. I learned a lot from it.” That is a great big signal that you’re not reading and you’re spam commenting.
3. Reply with your real name. If you comment with “Gold 4 Warcraft” instead of “John Doe,” people will REALLY think you’re link baiting/spamming and delete your comments. If you really want to optimize for “Gold 4 Warcraft,” then blog commenting with that as your name is likely not the SEO method you want. Comment as if you’re a real person.
4. Watch what referrer you use to visit a blog with rel=follow. An easy way to spot comment spam is if a person self googles to see if their newly created link shows up, if the visit came through Disqus (and has 100 similar comments to their names) or includes SEO or other search terms that indicates that you are looking for a chance to link bait.
If you want to comment for SEO, follow that advice so that your time is not wasted and you don’t get punished for spamming. If you are paying some one for SEO and they advice blog commenting and don’t follow the above advice, fire them and get your money back.