If you have twitter access, it's worth following checking out the current Josh Barro exchange. He's going back and forth with a Romney advisor explaining calmly exactly why their math doesn't add up.
Here's Josh Barro's article from Bloomberg.
In the linked article is a take down of each of studies the Romney camp claims to have on their side. It gets pretty technical, and honestly I don't understand it, but some of you might. What's going on in laymans terms? He concludes that the "six 'studies' on which the Romney campaign has based its defense of Romney's tax plan. Individually and collectively they fail the task."