I cannot speak to Big prizes because I did not win any, but I would say for the three times that I did win it was very fair and not biased (this was at WDW). All three were Dream Fastpasses. The first time was at AK on Dinosaur. As we were watching the briefing two dream teamers came in from the exit door. When the briefing was over they held us there and gave everyone in the room a pass (mixture of all types of families and people). Second time was at EPCOT and they were counting people getting off of Spaceship Earth and gave the fastpasses to the first X number (looked to be about 50) to get off from the time they arrived. Third time was at MGM and my whole Star Tours compartment got them. This was all during a 6 day trip in January.