I had my brake pads replaced at about 100k miles. I was hearing a noise that I thought was a bearing, and the mechanic came to the same conclusion, so I also had the bearing replaced. I drove the vehicle subsequently to work and back- noise completely gone. Driving to work the day after that, I experienced a loud droning noise that increased with wheel speed. Since my original mechanic was unavailable, I took it to another shop, where they told me that the new bearing was bad. Since it had less than 50 miles on it, I was able to get it replaced under warranty. Noise gone again. Within 100 miles of driving, I noticed another noise that sounds like it's originating from the same area (though it's different from either of the first two noises). I haven't gotten as far as testing it yet to see if there are any additional symptoms that suggest a bearing (turning the wheel doesn't seem to affect the noise, but it didn't on the first two either).
So, my questions are:
Is it possible that a faulty installation caused a bearing failure?
Is it possible that another un-diagnosed issue is contributing to any bearing problems?
Could something else be causing noise similar to a wheel bearing that was incidentally corrected while installing the new bearing (something loose, like wheel studs)?