Even the financial disclosure statements that political bloggers were required to post hadn't stemmed the suspicion that people's opinions weren't really their own. "Who's paying you?" was a retort that might follow any bout of enthusiasm, along with laughter - who would let themselves be bought?
When you hear someone criticize a policy on the other side, thats fine. But when you start hearing motive-mongering and demonization, stand up to it just as you would if it were something that was racist or sexist. If we avoid the demonization, disagreements can be positive.