If you want to see a few espisodes of the "building of links to guest posts gone wrong" show, just have a look at the backlink profiles of some mommy blogs heavy on guest posts. I have seen sites spammed to oblivion by people"powering" their guest posts. Just don't do it, if you guest posts isn't strong enough, you picked the wrong site. It's like PBNs, if they need additional backlinks, you registered the wrong domains. The really good stuff works by itself.