The thing is I see every spammer on here trying to create spammed comments which normally are automated bots giving no insight, no information and no assistance to any post they are on so why do they bother?
SEO guru’s out there (what they like to call themselves or Experts) tell people to do it at the same time does anyone ask them if they do it? Because in reality a lot of it is like here where you have Google searched for something to do with commenting and SEO they are looking for your page landings onto the article you read from them or to sell you a product nothing else. First rule of internet marketing is always to tell people how much money your making and exaggerate it (nope i don’t do that if you search through for my pages there were actually the incomes for my ad sense etc. from the day i wrote the article).
So if they are only using you for page readings so they can have the ad sense around the page what benefit is it to you?
Well here’s the thing about commenting make it useful, witty, interesting and although you won’t get a back link for it most of the time adding a link back in the body of the article to an article you have written of similar use or interest could build a bridge between you and the site your using. At the same time having signed into their comment system and having your website name in your name when hovered over means if other readers like your post there is a good chance they will click through to your site. That is the main use of the commenting system to get the most out of it. Put thousands of “useful” comments out there and ask the blogs you like if you can submit an article as most like me are quite happy to share other peoples content. At the same time don’t duplicate! Cutting and pasting from your own site isn’t good for SEO as Google doesn’t like duplicate content so write a unique article for the other site and everyone is happy in a positive way.