Been to various parts of the US. Met open racists on a few occasions. How likely you are to encounter them will vary by location, but your experience will most likely be great. There are many racists in America but most of them are not the kind who will choose some black tourist in the middle of the city to harass. You’d have to get pretty unlucky to get more than a snide look. Most of the people you will interact with as a tourist will be customer service reps, who, generally speaking, will be extremely cordial, even if they were to be the kind of American who has some issues with race. The one color Americans respect more than black or white is green. If you have money to spend, they’ll be only too happy to help you spend it. Cops will treat you better if you have money too, and not even in the sense of bribes. Dress like you have money and they’ll treat you like you do.
That said, non-racial crime is still very much a thing, especially against tourists, so keep to the safety of well lit, populated areas as much as you can unless you have a local to tell you where it’s safe.
Oh, and try some authentic Mexican food if you can. It’s delicious.
Monkey’s paw moment: they’re for STIs rather than mental disorders.