For lower end bikes, here is a comparison between a nice Trek 950 bottom bracket weld and a sloppy Schwinn Criss Cross bottom bracket weld. The Trek is a 1994, the Schwinn is a 1992, so it is not a difference in era. The Trek weld is smooth and uniform, the Schwinn is anything but... FWIW, the Trek was US made, the Schwinn Taiwan? (I am not sure).
