Using dummy cards on ATMs to find out if they suck your card in before using a real bank card

I have actually never had an ATM tell me the truth about why it rejected my card as long as I can remember. And the false reasons for rejection that are given sometimes match reasons that some ATMs warn they confiscate cards over. So yes, I have trust issues and seem to be developing a phobia.

I have also on one occasion asked for more than the bank’s limit. I did that 3 times consecutively and the bank’s AI algorithm decided that looked like fraud and froze my account. That’s poor judgement on the part of the bank but the ATM network makes similar poor judgements. When speaking to the bank, the banker actually did not know why the mysterious black box algo decided to freeze my account because the bankers themselves are kept in the dark about it. He could only offer guesses. He said “why did you try a different machine? That’s suspicious; you should have stayed with the same machine”. I had little confidence in his guesswork. So in fact he could not even tell me how to avoid getting my acct frozen in the future.

Not necessarily. The machine has a choice whether to give your card back or not. In Netherlands 4 out of ~17 ATM withdrawal attempts succeeded. A couple of the machines that rejected my perfectly valid and funded card did not have a motor, so there was no confiscation risk. A couple were Geldmaat machines, which do have the confiscation mechanism. They don’t disclose that on the machines but the website mentions it. I got lucky and Geldmaat returned my card. But the reason it gave for rejecting the card is the same reason some machines will confiscate cards. I was lucky I was able to get my card back and use an ATM by a different operator, which accepted my card. Had the ATM confiscated the card, I would not have had the chance to try other ATMs.

• Low-tech criminal inserts a sleeve into the slot that adds enough pressure that the motor cannot eject your card. The card works while it’s inserted so they can shoulder-surf PIN entry. User walks away without their card because it is stuck. Criminal returns with an extraction tool (like tweezers). They then have your card (and also your PIN if you didn’t cover your hand well). Obviously the card grab technique only works if the card ends up getting inserted completely into the slot. The non-motorised ATMs leave your card ½ sticking out, so you can always get a grip on it and thus are not vulnerable to this card theft.

The biggest threat is not criminals but the ATM operators themselves. ATMs that suck the card in have a card confiscation mechanism that is usually undisclosed¹. Some of the (foolish) reasons ATMs will confiscate your card:

• you enter the PIN incorrectly²
• the machine thinks your card is faulty or invalid
• some AI algo suspects your card is being used fraudulently

¹ I once encountered an ATM that had a sign posted saying “reasons why this machine will confiscate your card: …” and it listed the above 3 reasons. In that case, it was disclosed and I opted to avoid that machine. But usually it’s undisclosed. E.g. a vast majority of Dutch ATMs are all by the same company “Geldmaat”. None of those ATMs disclose potential for confiscation but if you look at the geldmaat.nl faq, they admit to it but they conceal the reasons, so customers don’t know what risk they are signing up for with those machines. When the confiscation happens you cannot get your card back. It’s simply destroyed by the ATM operator and you have to ask your bank for a replacement.

² (edit) incorrect PIN could perhaps be a good reason. If you are being forced by a thief to pull cash out, then deliberate incorrect entry could be a way to avoid paying the thief and the confiscation relieves you of repeated trials. But it’s still disturbing that banks are not wise enough to give people distress PINs (a special PIN that lowers the limit and sends a silent alarm signal, but pays out for safety).