Invalid Usernames/Passwords will not be imported. Username needs to be a valid e-mail between 4 and 80 characters with no spaces. The Password needs to have a min of 4 chars and max of 50 chars and it does not allow special chars. If you are trying to import multiple listings to the same account in your .csv but are using different passwords for each line in your .csv the import for the additional listings will have problems. You may find it easier to use the Import Settings to upload multiple listings to the same account.