Sales people are used to being measured by hard metrics, and management is very used to imposing and managing these metrics, and marketers are more inclined now than just a while ago, to have quantifiable measures.
Therein lies one of the challenges of social media.
To varying degrees, SM is not a great sales tool, but it is a great tool to build engagement, and engagement leads to sales, eventually, and amongst other outcomes. It can take the place of the face to face selling, and potentially much of the role of traditional advertising.
When on the web, searching for information, peoples bullshit meter is working, so their receptiveness to advertising may be no greater than in a normal mass media environment, the huge difference being the ability of web advertising to target information at those looking for it. However, on social media, I contend that the bullshit meter is at a lower level, perhaps turned off, as they are seeking to engage, not just seeking information, so information accepted takes on some of the characteristics of endorsement.