In his latest personal blog post, The decay and fall of guest blogging for SEO, Google's head of “webspam”, Matt Cutts, said,

Okay, 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.

He goes on to elaborate:

So stick a fork in it: guest blogging is done; it’s just gotten too spammy. In general I wouldn’t recommend accepting a guest blog post unless you are willing to vouch for someone personally or know them well. Likewise, I wouldn’t recommend relying on guest posting, guest blogging sites, or guest blogging SEO as a linkbuilding strategy.

So let's parse this out a bit to try to understand what Cutts is really saying. He is talking about using guest blogging as a linkbuilding strategy and he recommends that “you should probably stop” that. Google deems anything that seems unnatural will be treated as “webspam” and will be acted on accordingly. This used to mean that any links you built (i.e., didn't earn) would be “ignored”. But more and more frequently, Google has actually been treating those links that it deems “unnatural” with a negative weighting in its search algorithm.

In other words, link building is causing sites to be penalized.

They've made this even more ridiculous with their “disavow” tool – where web sites get notified via Google Webmaster Tools that they have unnatural links that they should get removed. The webmaster then goes to the web sites where those unnatural links are and asks the webmaster there to remove the links. If the webmaster doesn't comply (for whatever reason), the webmaster of the site being penalized uses the disavow tool to tell Google, “Hey, I don't want these backlinks to my site but the site owner won't remove them, so please — just ignore them.”

That sounds great–in theory. However, what happens in practice is that the webmaster for the penalized site goes ape shit and disavows all the links back to his site and good web sites are now called out in the disavow tool, leading Google to go after them.

It's a witch hunt where the witches are doing all the hunting, narking out all their fellow witches.

But I digress…

…Getting back to the topic of guest posting is dead…Cutts says that if you're using guest blogging as a tactic to “gain links”, then you should…STOP.

How will Cutts' “webspam” team determine YOUR intentions? That's a question that remains to be answered. In fact, it probably won't be answered explicitly. As Google always does, it will over-react and punish all guest bloggers. Then, the vocal ones (you know, the ones that pay Google a lot of money in advertising) will cry foul and Google will flip-flop and grant them an exception.

This will be done for a handful of guest bloggers. But the majority of guest bloggers will get hammered, and guess what they'll do:

STOP

Yes, they will stop writing posts for others.

Oh, by the way, the web site that published the guest post will get punished, too. You know, arrest the John and the prostitutes.

Now, I get why Cutts wants to cut out guest blogging – most guest blog posts are crap. He does imply that you have an “out” if you know your guest bloggers personally and can vouch for them (suggests an “avow” tool, no?).

So what to do?

Move on. Fuhgettabout Google. (Did I just say that?) Guest blog if you want – by doing the proper outreach first. Get to know–intimately–the sites and publishers for which you want to guest post. Build a relationship. And when you do get the awesome news that you can write a post for somebody else, treat the opportunity for what it is. Write the best damned post you can. Go all out. Make it awesome!

And look forward to direct traffic back from the source site to your own, where you will be greeted by visitors who are perfect for your content on your own site.