Matt Cutts in his recent video, explained how to avoid penalties caused by blog comments, the question was about building relevant blog comments from themed blogs, do they still cause penalties or against webmaster guidelines, if built from relevant or topical blogs.
Matt Cutts giving his own example explained a few points to take care of while doing blog comments, he said that he himself does the comments to take part in discussions on blogs and leave relevant links from his own blog posts giving users more information. There is nothing wrong with it, but the real name should be used instead of keyword anchor text as well as the number of blog comments ratio in your backlink profile should not reflect that comments are part of the link schema.
As we have seen that blog commenting has been a favorite method for marketers to take part in discussions and leave their views while also earning backlinks to their website. But some used it to the limit for spamming search engines with anchor text-rich keywords, after that Google added it as part of their webmaster guidelines and termed it as “signature links”.
Today Matt cleared that blog comments with real names on themed blogs will not cause any issue or penalty to your website, but at the same time, you should not keep building blog comments and your link profile should not show most of the links as blog comments only, backlinks should also contain natural organic links as well.
It is advised to take the advice of a professional blog commenting services agency.