Is It Racist Only When About A Black Man?

Video - Obama witch doctor image racist?:

Let's see... The stereotype of a witch doctor has them dancing around while making noise and having no benefit to the patient.

President Obama has been if not dancing, at least making a lot of noise about the economy but has caused no benefit to the economy other than helping the CEOs of some banks, automakers and the unions.

That sounds like a fair comparison to me.

But...
African witch doctors are black.
President Obama is black. (Well, half-black)
Does this make the comparison of the two racist?

How about if President Obama was white? Would it still be racist?

When the liberals called President Reagan's economic policies "Voodoo Economics," no one called them racists... Yet I believe that most if not all voodoo practitioners are black.

So is it racist only when it is about a black man? On the other hand, is it racist only when said by a conservative? Since President Obama is also half white, does this mean that it is only half racist?

(Via CNN.com.)