I think most people find they have a bearing problem only when it fails. You can jack the axle just enough to clear the tire and do a quick check for excess slack and if all seems good there,spin the tire and listen for any unusual sound. If you've ever heard a bad bearing in this manner it's easy to recognize. This can give a little piece of mind but is not foolproof.
I have done this on occasion, but still fear the dreaded failure on the road. As stated earlier, all can seem fine until someone flags you down and you see the smoke.