Where did Schwinn manufacturing stop and "farming it out" start?
So many components said "Schwinn Approved" on them. I.E. custom for Schwinn, but did they make them? Especially moving into the later years as they started importing bikes and frames.
Certainly some companies such as Murray made bikes with other labels on them.
But... yes, one would think a seller would pay attention to the label on the bike. A bit harder to tell if it has been repainted, but still it sometimes has the brand embossed somewhere on the frame.