Blog commenting has been a big spammy technique to build back links, due to ease of automating it with tools. Many bloggers often see so much spam in their blogs that they completely turn off commenting. The question is that if Blog Comment links actually work for SEO?
The short answer is that NO. In most cases these links have a NOFOLLOW tag, which means Google will not count them towards a link. However, even if they don’t Google can detect Blog comments with their algorithm. In fact, if you do too many blog commenting, your site may get penalized.
So stay away from blog commenting!
However writing articles for your own blog and as a guest post, is a better way to build quality links. Be advised that Google also is against any kind of paid links or artificial linking methods, so do not write articles for SEO purposes, but write articles to get traffic and hopefully people will start linking to you when you write high quality articles.