I used Priceline at least 80 times in the last 5-6 years and have only once known that we were put in the special "Priceline section". That was on our first stay for one week at a Clarion Hotel near SFO.
Another time we used Priceline for a 30 day road trip and stayed at different hotels nearly every night-some for only $12/night. At one Best Western in Georgia we were accidentally given a room that hadn't been cleaned.
These were the only negative PL experiences I recall, including at least two car rentals through PL.