Ideally, ball bearings should have zero free play. This can be approached but is hard to get unless all bearing and wheel hub components are in perfect shape.
If you've ever adjusted automobile tapered roller wheel bearings, you know those have a torque rating. Sometimes this is like 15 foot pounds. This initial pressure seats the bearing and move any extra grease away from the bearing surface. Then instructions will tell you to back the nut off perhaps 1/8th turn while spinning the wheel, and lock everything down. This 1/8 turn provides proper clearance, which is close to zero. Some engineer calculated these instructions.
I dont recommend cranking down 15 Ft/lbs on the little ball bearing moped wheel bearings.. a pound or two will do.. but i do recommend using that general procedure. Clean, inspect everything before starting. Something serious enough to cause a bearing noise should also be very noticeable to the naked eye. If everything is OK, use fresh grease and go for it.
I don't see how applying a brake could silence a bearing noise unless damage to the bearing or wheel was extensive. My guess is you have a brake problem of some sort..