Guest blogging was one of the SEO tactics that were used and were considered as a badge of honor for the ones writing the guest posts. As the quality declined, the poor quality content through guest blogging increased.
In 2014, it is not recommended to go for guest blogging as a way to gain links due to the decline in the quality of the content and considered to be as a spammy practice. Earlier, guest blogging was considered to be a respectable thing but due to the wrong practice being followed to attain the links, the guest blogging has no relevance now from SEO and Google’s point of view.
Due to the low quality guest blogging, it has been hurting the uneducated website owners, as they are the ones who could not identify the spammers who are offering guest blog posts and are unaware of the negative effects of those spam blog posts on their sites. And due to this, now such websites with spam guest blog posts are getting penalized.
However, there is still a scope for gust blogging, it’s just that the site owner should understand and identify the quality of the content offered by the guest blogger as there is still the existence of high quality guest bloggers.
One can invite high quality guest blog post, which can be used as a tactic for driving the traffic. Though, it will not work from SEO or Google perspective.
Read more about this topic at Matt Cutts Blog