I do not know about how google treats links in signatures in forums but here at DaniWeb you walk a fine line with what you put in your signature. As for blog commenting, I use WordPress for the blogs for my customers and Wordpress allows you to review comments before they are posted and at that point you can identify them as spam and exclude them. I believe some of the other CMS's work the same way. That being said, I am not certain what how Google views blog commenting.
MktgRob
Nearly a Posting Virtuoso
1,294 posts since May 2009
Reputation Points: 18
Solved Threads: 4
In my opinion, it really depends on how you put your anchor text in blog commenting and forum signatures, and whether they are do follow or no follow. For google, signatures and blog comments are considered spam if deliberate links.
leahmarie
Junior Poster in Training
94 posts since May 2009
Reputation Points: 10
Solved Threads: 7
I don't think so signatures in blog comments & forum are spam.. because it is the blog owner or forum owner which decide whether the comments / signature is spam or not. If he reports the spam to the google then it may be harmful.
seoindia
Junior Poster in Training
78 posts since Oct 2009
Reputation Points: 8
Solved Threads: 3
Here is how you get your signature link valuable to google search engine and not considered as spamYour anchored text must be relevant to your website or webpages
the context of the forum in which you have your signature must be relevant (if your website is about game with game website signature, and you post it in irrelevant forum like cosmetic forum for example) then your signature is useless and considered spam
ljianyih
Junior Poster in Training
58 posts since Nov 2009
Reputation Points: 14
Solved Threads: 0
One more thing in addition to what i've posted. In order to get the most out of your signature (besides the 2 points i mentioned) if the links (any links besides signature) are coming from forum or website with high traffic or ranking, you get a more valuable links from the search engine.
ljianyih
Junior Poster in Training
58 posts since Nov 2009
Reputation Points: 14
Solved Threads: 0
I think Google doesn't consider either type of links as spam. It assigns some insignificant value to them but that is based mostly on the credibility of the blog or forum. Dumping links on spam forums and spam blogs can actually be harmful from an SEO perspective.
If you post a comment on a blog that is not deemed important than your link will be deemed unimportant. Same for forum links.
As previously suggested, there is a factor considered as relevancy that can add some small value to the link.
Either way, both forum links and blog comment links are of very little value in the bigger SEO picture, even in huge volumes.
canadafred
SEO Consultant
1,021 posts since Feb 2006
Reputation Points: 192
Solved Threads: 28
Signatures are definitely treated as spam in forums and blogs and many forums even ban the membership for the same reason.
Angela12
Junior Poster in Training
57 posts since Aug 2009
Reputation Points: 10
Solved Threads: 0