[Msquared]

Usually you should be able to produce some play in the bearing with the car up on a jack and your hands on the outside of the tire. A bad bearing would have equal play in all directions. That said, if you have the tire off the ground and spin the wheel and hear metallic grinding sounds, that means a bearing is going out regardless of play. Don't confuse that with the pads on the disk, though. You can pull the caliper off and spin it again to be sure.