I'd guess legit about 60/40 real to not-real. Of the 60 real, I am guessing there is a healthy percentage, call it 1/2, who do it just to be outrageous and see people freak out ... the same kind of people who like to just burn or vandalize shit. Maybe some racial motivation, but mostly just for the joy of making everyone freak out. The other half of the 60 actually have problems with dark people. Spend some time in central Florida and you'll see what I mean.
These are the results of my scientific, peer-reviewed study. This is real scientific shit so you know it's true.