How prevalent is anti-white racism in Haiti?

There is no such thing as anti-white racism in Haiti. Haiti has a long history of foreign intervention and occupation and Haitians are therefore very critical of foreign interference. This, however, does not mean that people are hostile towards foreigners. As long as you treat people with respect, you will not have any problems.

I stayed with a Haitian pastor and his family and was the only "white" person in the community.  I never experienced anti-white racism; on the contrary, I felt welcome and safe.  (This was not a rich area.)  As is true anywhere, you have to be careful where you go.

Actually one of the things we (Haitians) don't advertise is our hospitality! They would help you like their own relative.
But, like any other country there are places you avoid. As a matter of fact Foreigners are treated much better, per se!

Just returned from another trip to Haiti.  Although we were warned away from some areas and travel after dark, we traveled to outlying areas and were treated very well by those we met.  I love Haiti and her people (although I find the government's treatment of her people predatory and distressing.)