One major difficulty of running a search engine marketing campaign is the fact Google's algorithms and patterns can seem rather opaque. Besides the analytics and metrics that are available to content marketers, most companies can only judge their failures and successes on their ranking in terms of results for keyword searches.
For instance, when a link that directed users to a business' website comes from a questionable source or is suspected to be part of a link farming or sharing network, the only notice an organization might receive would be a drop in page ranking. This makes it hard for companies with vast sharing campaigns in place to pinpoint which connection is questionable and should be removed.
However, Google has come to understand this is a difficult task and is making it easier for companies. As of 2012, the search engine began notifying companies when their links aren't valid, letting them know these will harm SEO rankings. In fact, over 700,000 messages were delivered to businesses, indicating particular links appeared "artificial" or "unnatural," according to Search Engine Land.
This means companies can take heart in the knowledge that they'll be told when something in their link network appears amiss. However, it doesn't absolve inbound marketers from studying the connections they share with organizations and determining if any of those groups are engaged in black hat practices.