[ALR-bishop]

There are a lot of uncorrected error cards. SCD list a bunch of them . If the error is corrected it is usually listed as a variation. Sometimes errors are unintentional but occur because of an intentional change in the printing process ( 62 greenies) and sometimes they are just defects in the print process ( 82 Topps Blackless). I think the blue Aaron is a recurring print defect, but it is a variant to the regular green background card.

On the other hand some mere print defects, the 52 Campos, the 57 Bakep, and the 58 Herrer have achieved superstar variation status in the hobby.

Everyone just has to collect what appeals to them. Variants of any kind appeal to me, even if they are just glorious print dots.