A friend of mine in college worked for a dating website. His job was to act as a couple of hundred different women. He maintained their profiles, 'winked' at people, answered emails, etc.
These women of course never existed, his job was to make it seem like there were more women on the site than there actually were. Pretty sleazy job and we always gave him grief about it. But he said, 'what the hell, they pay me to work at any hour and from my dorm.'
So I'd guess it's entirely possible there are such shills in the world of politics since there's so much money in politics. (Certainly more than in on-line dating!)