is paid links, he is not a coherent and content link, and blog theme misfits. For the normal chain, in a blog will usually have the link (experts, website) introduction, at least one paragraph in the introduction: who is this person, why in your blog, and will not be paid links.
Matt Cutts said: when we encounter a spam report, we will study the SPAM team behind the scenes, occasionally distinguish the chain of garbage and large-scale paid links have different standards, which is the distinction between whether a blog is a standard text.
source: Lou loose blog text address: 贵族宝贝lusongsong贵族宝贝/blog/post/771.html
Matt Cutts also said that at the same time, you can do marketing, embedded keywords anchor text to join them, but rel=" nofollow", if you really want to live up to the user, but also to provide relevant content and topic.
he gave a method to judge, I think it is the most important one: