Is blog commenting effective?

One method of cheap SEO that is always mentioned as a way of getting baclinks is to use blog commenting to create links, especially from prominent blogs. However, looking around at the scuttlebutt regarding SEO these days, it seem like blog commenting has gone out of style as an SEO method. So what’s the truth?

It Does Count, But Not As Much As Other Backlinks
The people who run Google aren’t stupid. They know that the backlinks you can get from commenting on blogs and or forums are just about the easiest ones to get. That said, they also know that the blogs with high page ranks (usually 5 or better) actively moderate their comments and will delete the “drive by spammers.”
By the way, in case you were wondering, the “Drive by blog spammer” will write something like “Thanks, I learned a lot” and then leave a link back to his or her blog (which often has no relationship whatsoever to the blog being commented on).
Well moderated blogs delete drive by spammer comments and since Google’s engineers are aware of this, they take that into consideration. They may also take into consideration by the way whether your blog or site matches the niche of the blog you commented on, so it pays to comment within your own niche.
The No Follow Comment Problem
Another issue which has made backlinks less effective on blog comments is that many blog owners (in an effort to make spamming their comments less tempting) have taken to setting their comments to “no follow” in the robots.txt file for their blog. This effectively means that your link will not get indexed and will not count as a backlink.
Why You Should Comment on All Blogs Anyway
Now, all that having been said, there are very, very good reasons to comment on all blogs anyway. First of all, some blogs change their policies all the time and a “no follow” blog today could change it to “index, follow” tomorrow.
Secondly, and much more importantly, you must remember exactly why people comment on blogs to begin with – because they have something interesting to share with other readers. Well guess what? If you have something interesting to say, those other readers are going to click the link and it doesn’t matter that the link is a “no follow” link.
Plus, if you add a truly useful comment to a blog post, it’s not uncommon for the blogger to decide to modify the post and put a link back to your website saying “so and so makes an interesting point. See his site for more information.” This is golden – those are the kind of backlinks that are actually worth much more in Google’s eyes.
How to Comment Effectively
Generally, there are two theories about commenting on other people’s blogs effectively. Either comment with something more than just a few lines (i.e. a paragraph or two with really useful thoughts) or, write a blog post on your own blog and then comment, providing a link back to your blog post.
Needless to say, if you choose the second option, you’ll need to include a link back to the original blog post on your blog. Either of these methods should get you past spam filters and human eyes which moderate comments.
The one other thing you should be aware of however is that you should be writing comments which really are relevant to the blog you are commenting on and you should (ideally) comment on blogs which match your own niche so that the readers of the comments will have a real reason to visit your blog or website, thus increasing traffic (which should be your ultimate goal).