The wear indicator will be much louder than some dust or something in between the pad and the rotor. If it is screaming at you like a child (male or female), it's the wear indicator. If it's just a little bit of a squeal, it's most likely some dirty rotors. Get some brake cleaner and douse them. If it doesn't go away, separate the calipers and inspect the pads. On my track car I've had a pad crack in half while in the caliper and it was squeaking as if the rotor was dirty. I'm assuming cheap pads could do this on a daily driver as well.