Guess I was just lucky (or unlucky)... it is not knowing what you are talking about, it's your experience. I have only bought about 6-10 packs of Bachmann wheels, and more than one in 20 had what I considered an unacceptable wobble. Since they were cheap, I was not upset, but I don't want to buy more. They were only from 2 different stores, so a small sample. I have settled on mostly cars that come with metal wheels in the first place. I do not like the finish on the Bachmann wheels, and they appear to be cast not machined, but you get what you pay for.
I do not think that ball bearings are all that they are cracked up to be myself. On grades they really make no difference, only rolling resistance on the flat. Most people are working the train harder on a grade.
Regards, Greg