If you bake a sweet creamy cake, then you don't use salted margarine or salted butter or the whole cake will be salty.
Its happens not only to me twice, once with a chocolate cake and once with a black forest cake, it also happens to other customers I know.
If you produce something you should have a quality control. It is fine for me to make a mistake, but if you make the same mistake more as once then it is a issue.