Dark spirits?

When Obama attacks the Republicans, he reverts to racist, anti-black language. Anti-blackness is embedded in his white half.

Why are the terms “dark” and “black” associated with bad things? If the Republicans were full of “light” spirits, that would be ok?

Barack Obama: “Dark Spirits” Have Taken Over Republican Party

You know how them grey people trying to trick us with they slickery?
Slick with they trickery?
Peep the connotations of that, nah-meen?

It's like black ... angry ... dark ...
Sullen ... depressed ... wicked ...
off, blacklisted, black cat is bad luck,
bad guys wear black ...
Must have been a white guy who started all that!