Does Blog commenting really helps improving page rank?

I had researched a lot on Blog commenting, no doubt whole world is shouting and suggesting it as best way to build links and improve page rank for your blog or your website. But does it really helps improving page rank?

I am researching on different aspects of SEO from last several months and blog commenting is one of them. I had read lot of articles on blog commenting. Some says that it will improve back links for my blog or website & will increase my website's page rank effectively. While few suggests not to leave spam contents. There are lot of peoples who says they are experts in SEO and no doubt they are. But no one has confirmed that does Blog commenting really helps in boosting page rank.

There are lot of suggestions; some says that we should not use directory services for making back links as lot of poor back links reduces page rank. Some says we should go for some paid services while some suggests writing quality contents for your page rank. But no one has answered what are chances for unique contents. For example I am operating a web designing company and start my blog by writing few tips on web designing. But I am not the first person in this world who will give you tips on web designing, there are hundreds of thousands peoples who had already written articles on web designing. Hence there is almost zero chances of uniqueness of contents on web.

Many blog writer knows that what they are showing to world is not the truth, but they shows it to world. Newbies don't knows the facts and they start reading their articles and generate traffic on their website or blog. As a result page rank of that website or blog improves and writer says to check the page rank of their website or blog as a proof.

Now it’s time to know about the truth of blog commenting. You will be surprised to know that most of the blogs use the rel="nofollow" tag for the links in comment and in body. If you are commenting on a blog and blog is running on blogger then your all links will automatically use the rel="nofollow" tag, so you'll receive no page rank boost. You can check this by clicking here. And the blogs which are not running on blogger are regularly optimizing themselves for rel="nofollow" tag. It’s really hard to find the blogs who do not use rel="nofollow". Especially if the blog has good page rank on which you are commenting for back links then it is just waste of your time and energy.

Last words: There are lots of if’s and but’s on blog commenting for improving page rank but there is nothing which guides you on it. Everyone is just revolving you in a circle on this. In most of cases blog commenting does not helps improving page rank.