"Dog-whistle politics" is a term imported from Britain that implies politicians use language with two frequencies, one for normal people and one for less savory constituencies. Dog-whistle messages are real. But dog-whistle spotting can be hard -- you're listening for things that, by definition, normal people cannot hear -- and prone to wild misinterpretation.
For instance, Gingrich has been talking about food stamps and child labor for a long time. During that time, he also worked harder than most GOP politicians to reach out to minority groups, even to Sharpton. Does he phrase things too provocatively? Absolutely. But he does that about everything from tax cuts to moon bases.
When Gingrich came down like a ton of bricks on Juan Williams in the South Carolina debate on the food stamp issue, liberals instinctively saw it as a racial transaction, pure and simple. And although I have no doubt that racists enjoyed seeing Gingrich belittle a black journalist, there's zero evidence that Republicans overall cheered for racist reasons. They've cheered Gingrich for attacking white moderators from every outlet, including Fox News.
And to the extent there are racial implications to what Gingrich proposes, they're no more racist than remarks made by prominent African Americans who see the culture of poverty perpetuating poverty.
But for reasons that say a lot more about the weaknesses of the first black president, liberals yearn to hear racism where it isn't to make this campaign into something more exciting than a referendum on Obama.