we have had some bug issues at AKL and WL. this was in the evenings. At WL, the bug issue was also present on the boats to and from the MK. I'm guessing that anywhere there is water and greenery, dusk can bring on the skeeters. no matter how much spraying Disney does, mother nature will always win out in the end!
but to be honest, I don't think I actually brought the repellent into the parks with us. We happened to be staying at those resorts, and if I knew we would be outside at night, i would spritz everyone w/the spray before leaving the room.