I always use decent pads and new rotors with great results: that way the car always stops like it should without squeaks and regardless of weather, heat in the rotors, etc.. Only time I've reused them is when they have not worn as they are good ones from a wreck and you're changing the pads or have worn your existing pads without wearing the discs (wrong pad compound). A good option perhaps if fitting crap pads to use them up... pfft!