Google issues lots of different manual actions or penalties on sites for various reasons. But not all those manual actions lead to a ranking demotion in Google.
Google's Matt Cutts said this on Twitter that "not every manual action gives a ranking demotion."
Here is the Tweet:
For most experienced SEOs, this should not be something new. But it is nice to have on record.
I experienced this a lot when it came to my link scandal here. I was a bit surprised then to see no ranking change in the site after removing the links but truth is, I did not see a ranking decline by having the links. Although I thought the internal link flow was impacted, so I was confused a bit.
Forum discussion at Twitter.