I am sorry for what I stated about goyishe stores not accepting returns on sale items,I meant to write clearence items.
As for clearence what Wolfish states is basically correct, I have a relative who has a store and takes credit card on everything but not sale items since it cuts into increases the loss by to much.
Incidentally, I would posit that if more Jews would be makpid to purhase from Jewish stores then the profits would go up allowing stores to increase their profits and institute better return policies.