Spam is spam whether the search engine can follow a link to it or not.

If you haven't anything worth writing about on someone else's blog comments section then don't write it. If you want to write a comment on someone's else's blog for the purpose of getting a couple of your links followed and valued by the search engine then you are a spammer.

These type of link building schemes never amount to much anyway, even when the stragtegy is deployed in huge volumes. A person interested in getting their webpages highly ranked in the search engine results pages for any meaningful keyphrase can make much better use of their time by performing the standard ethical SEO stuff: rewriting some stagnated Headings, crafting web page Titles and Meta Descriptions, tweaking paragraph content, working with image names and attributes, making the web pages more user friendly and accessible or just by building a couple of new web pages and introducing them to an already powerful pool of well-linked webpages within your own web site.

Addtionally, if you want to get an SEO boost out of blogging, write your own. New content is what the spiders look for. Also, if you find someone elses blog content to be especially pertinent to your website and it will enhance your overall website rather thant detract from it, set up an RSS feed from that blog directly into your own website. Again, another spider friendly way of adding fresh content without spamming.

Wordpress had the 'nofollow' attribute by default. This gives you protection against spam. And as for the .NET blogs, it appears that the 'dofollow' is the default tag. But a spam message is a spam message. And the irony is that inspite of posting some very good and related comments, it is likely that the dofollow blogs will not entertain your comment. This is because behind 1 useful comment, there will be 99 useless comments that say - I Like You And Your Post.

What an abuse.

good tool to search dofollow blogs http://dofollow.radpixels.com/