On occasion, a negative listing that was recently deleted will be eventually verified by the creditor. The new Fair Credit Reporting Act requires that the credit bureau inform you before the re-report a previously deleted listing. The FCRA also makes it more difficult for credit bureaus to re-report listings. Because of these factors, it is fairly rare for listings to come back on once they've been deleted.
If an item is re-reported, it is a simple matter to challenge the listing again at a future time to press for permanent deletion.