Much of the campaign staff assigned to Palin came from Romney staffers who hired onto the McCain campaign after Romney conceded defeat in the primaries.
Their interest in demeaning Palin was to remove her from consideration and keep the field clear for Romney in 2016. Whether they were acting on their own -- or with Romney's blessing -- is uncertain.
Most of the McCain staffers who actually dealt with Palin and were in the position to make comments based on actually knowing here were long-time McCain loyalists.
Did somebody who worked for Romney or supported him in some way bad-mouth Palin? It would be surprising if somebody like that didn't at some point or other make negative comments. Politics is politics. And in fact, we do find, when the 2012 campaign was getting started in 2010, negative comments about Palin from Romney staffers. That's politics and it's what campaigners do to those they're campaigning against.
But the original story, that somehow back in 2008, McCain staffers who backed Romney were telling stories out of school in a smear campaign was the creation of a campaign consultant whose firm had worked for McCain. So far as I can see there wasn't much substance to it, especially since McCain loyalists were attacking Palin loudly enough then, using their position as those who had some interaction with her to justify stories that would put the blame for their ticket's loss on Palin. It wasn't Romney people who circulated those stories, as far as I've been able to find out.