Well if am not wrong google get catchy on commenting links and start penalizing those links. Two of my site get out of ranking, and what i believe its bcoz i have a lot of links coming through quality comments.
bro. if google think that any website links are getting in spam so they block their website in google results.
I do not think so. You get 'banned' from Google because it was too much to make comment link at the same time and by using the same IP. As a result of Google you are considered a 'spammer' ...
Sometime I think SEOers thinking too much about how indexing, how deindex, how make traffic, How comes my website drop... Let it be, sometime I hate Google, but please Google do not hate me and my website ^_^
Blog Comments are not recommended for SEO . If you just need a Backlink then do-follow blog comments works fine but if you need PR and SE Ranking then I believe you should concentrate on blog article and one way linking .
blog commenting is a part of SEO but you are true that the links should be from DOFOLLOW. Google sometime banned wrong sites too
Nah, I think that Google penalize comments that are too many, and too fast. If all you always say is "nice post" or something like that, it is consider as spamming. But if you take the time to talk about the subject, and make a good comment about it. You should get reward for your work...
Web Dev is saying true about commenting. spamming comments never count in google cache and some times this also can make your site banned but this happen in very rear cases. Always try to give a comment relevant to the subject and should made some sense.
Google "slap" or "penalty" is a myth. If you have a webmaster account set they would notify you of wrong doing. Google is pretty upfront about everything accept their natural ranking process.