Comment by ryderm

This isn't quite true. It is up to your issuer if they decide to approve the transaction despite failing AVS or CVV checks. Often they will decline the authorization, but depending on their risk signals, might decide to approve it. Then, the merchant (or the processor they are using) can decide if they want to let the transaction go through despite the failed checks, or call it a decline and reverse the authorization, which removes the pending charge. Crappy terminals might cause the pending authorization to sit there for 1-3 days by delaying or not sending the reversal, but in general that shouldn't be the case.