There is always a strong resentment from Dominicans against Haitians who might be in competition for jobs that Dominicans might perform.Never seen that. It has to be different at the various locales.
For instance, up in Samana (which has the darkest residents, having been "sent" up there to "fish" when Trujillo cleared the land for the park in St.Dom. Este) when the A-I hotel up there was bought and redone as the Grand Bahia Principe in Portillo, the local Dominican construction workers protested daily - because the owners of the hotel had brought in a crew of Haitians... they put the Haitians on the site - left them there to work- did not pay them for 24 days... And paid them about US $25 a day. The Dominicans WANTED the work -but Would Not Do It for that price - which was HALF of what they would expect to get.
There are laws about what percentage of Dominicans/Haitians any businesses can employ.
I doubt anyone minds if there are Haitians in the fields in Constanza spraying the fields with whatever chemicals without any sort of face masks... Nor those Haitians who do the construction in SD, living in the buildings that they are working in - since most of those jobs have Dominicans in charge of the labor teams.
But - for quite a while - there were a lot of Haitians who had jobs out in Punta Cana because they had language skills that Dominicans simply did not have... It is perhaps because they live in a dual language country that Haitians pick up other languages quickly.
Here is a report I wrote many years ago about one of the Haitian communities in the Capital. It is old but I doubt that the situation has changed.

HAITI-DOMINICAN REPUBLIC: Solace in Solidarity
Elizabeth Eames Roebling and Auguste Cantave