I've been told that you can find if a site is dofollow if there is no "nofollow" tag in their source. (ctrl + u). So if I comment on this page then my link has link juice because it is Dofollow? Seeing as there is no "nofollow" tag in the source.
that may not be the case always. if there is no comment on a blog article and if the blog comment is nofollow, then the page will not have any nofollow in the source. there has to be atleast one comment for you to know whether the blog is nofollow