The venerable Mister Cutts said:
The decay and fall of guest blogging for SEOOkay, I’m calling it: if you’re using guest blogging as a way to gain links in 2014, you should probably stop. Why? Because over time it’s become a more and more spammy practice, and if you’re doing a lot of guest blogging then you’re hanging out with really bad company. Back in the day, guest blogging used to be a respectable thing, much like getting a coveted, respected author to write the introduction of your book. It’s not that way any more.