I was just in Playa Dorado at Gran Ventana for a week 3 weeks ago and I'm fine. There was nothing going around while I was there. And I ate (and overate) the food, especially salads and fruit.
I'm heading to breezes in July and checked with my travel agent and she said:
Sunquest said that there is nothing to worry about. What had
happened was that the resort water boiler was broken and sunquest just
stopped sending people there as a precaution to customer service issues.
The resort was never closed at all and every other tour operator was still
sending people to breezes. The problem has been solved and you have
absolutely nothing to worry about!
I believe it's rumors as some people were still on the resort in rooms that had the water working.