Is blog commenting effective for SEO and web traffic or seen as spam? (after google panda and penguin update)?

[Khuzaima]

Its very simple, always comment relative to the given content.
Example: If the content is about curtain fabrics and you comment about your business besides curtain fabrics i.e. sports shoes then this would count in spam.

Blog commenting is a major part of SEO but you must not make a habbit to do SEO only by help of blog commenting. Do it 2-3 times a week.

As far is google panda & penguin are concerned, its just saying to bring your site to a competitive keyword in search engine, your site must contain that keyword in the unique content uploaded on your site/blog. Making too much blog commenting will make the web-address spam if its on irrelevant posts.