Neverlube bearing replacements

I don't know if the analogy to changing car wheel bearings really holds for two reasons. First, no car I've ever had in the last forty years had as crude a suspension as my trailer's, which has broken springs, had all bushings wear out and has had brake shoe problems that seem inexplicable. But beyond what appears to me to be quality below the standards of a car, second, I ride in the car and therefore have heard those few time I've had a car long enough for a bearing to go out. You first can hear the low frequency rumble well before total failure and the grinding that accompanies it. I can't hear what's going on on my trailer axles. So I just can't muster the same level of confidence for my Dexter axles before going on a long trip that I can my car I drive almost daily and therefore remain very familiar with its maintenance needs.