Matt Cutts, answering a question “How can I guest blog without it appearing as if I paid for links”, today published a video explaining what real or organic blogging is.
Matt explained how his team distinguish real blog posts compared to paid posts by reviewing spam reports. Matt Cutts said that organic blogger or blog post will not be off-topic, if the subject of the post is not relevant or themed with rest of the contents of website; it means the blog post is not real or organic. So it is clear that if you are doing guest blogging and want to get escaped from Google, all you should do, is have published your posts on themed/niche blogs.
If a blog post does not have a suitable author paragraph explaining about the author of the post and why have you invited him for blogging, this is also another indication, a real blogger will have suitable author section linking back to his social accounts or website with branding etc rather than keywords.
How Google measure spectrum of quality, Matt further advices that an organic blog writer will not have contents filled with keywords and have keyword anchor text linking.
In end of his video, Matt suggests not do guest blogging as full day job, he says to do it in moderation, but with quality.