How effective is leaving comment links?

[SparkplugDigital]

Has anyone seen evidence of rankings improvement from leaving do-follow comment links or is it a waste of time?

[scanlin]

You can't go crazy and do just that, or do 10,000 instances of that with no other types of link building. Yes, having comment links looks natural. Up to a point. And it depends if the links are on human moderated boards or on spam farms. The latter will produce no value. If you can get a link to pass moderation from a credible site then it has value. Your comment will need to add to the discussion and often the moderators won't allow links in comments or they will no-follow them to discourage spammers.

[vforvinnie]

I think comment links are more valuable for building relationships with other sites and for branding with targeted audiences.  I think the links themselves are diluted as far as SEO value goes.

Google knows when links are comment links, and might even disregard them all together on certain sites.  If the blog has an editorial policy (needs approval for comments, or deletes spammy ones) they might offer more value.  Plus the links are generally at the bottom of the page, and may send less value.  It really comes down to a case by case basis.  I would use the same criteria for blog posts as I do for links in general:

-Page rank or moz rank?

-Regularly cached pages from the blog in the index?

-Good content?  Is it related to your site?

I would say if it's good related blogs it's not a waste of time, but don't expect to climb up the rankings just because of those links.  I also wouldn't differentiate too much between no follow and do follow links.  Google still tracks the no follows and having some will look organic and would still give you some of the networking and branding benefits mentioned above.

Vinnie

[AlanBleiweiss]

I'll build on what Mike said in that comment links are less valuable than they used to be due to the proliferation of this as a spam tactic.  And I expect they'll become even less valued as time marches on.  For the most part the value is weak at best nowadays, and requires a lot more time and effort to get right given the attention this type of link has garnered from Google due to the spam issue.