[timerickson]

Yes, the OP is specifically referring to "Sponsored Stories" – the concern and alarm is raised because the user has no way of knowing what stories are being attached to their name, or even that its happening at all.

As for your later point, your assumption that all users know these posts are advertisement and that users understand their friend didn't really like a post about 2 Girls 1 Cup – is patently false based on OP's own personal experience. His mother saw a Sponsored Story by VICE about "Penis Waffles" that had his name attached to it. When she saw the post, it looked to her as if he had liked the story/post and urged him to take it down.