Don't they just turn when you're driving?
Disk brakes? Use an indicator to see if the faces wobble. You'd feel shuddering when braking and get steering wheel shimmies. Muh van dos it. I've heard new rotors are all made in China and will warp as soon as you heat them up.
Hay maybe I'll affix some sandpaper to the pads, use a threaded rod to incrementally depress the brake pedal, and turn the wheel with a honda and a pulley. Voila, ground in place.
Grease on brakes makes them feel grabby and can cause pulsations during braking, I've heard. Interestingly, it has the opposite effect of grease on any other surface.
There's probably a metal tab on the pads or pad holders that's designed to rub on the rotors and cause squeaking when the pads are worn. Just make sure you didn't...idk... position it wrong when changing the pads or something.
If they're drum brakes I'll have to get back to you. Haven't checked mine at all since I bought the truck a few years ago. Safety first!