ATMs very rarely inform users before they put their card in the slot whether it’s the kind of machine that uses a motor to suck your card into the machine. If yes, then avoiding the machine is a good idea.
The question is, how do you find out in advance whether the machine has a motor? Obviously if you test it on your actual valid bank card that you intend to use for the transaction, you may not get it back.
So my first thought was carry expired old bank cards which can be sacrificed. Stick the card in and if a motor pulls it in, hit the cancel button and try it on the next ATM until you find an ATM that does not suck the card in. This still has issues. The machine can vary well confiscate the card merely on the basis of being expired (thus invalid). Sure, it’s a sacrificial card but I don’t have 100+ such cards to spare. And also those dead cards will have my name on them and the ATM network could blackball my name.
So my next thought is to cut a rectangle from a plastic food container to use as a dummy card. It’s still dicey because criminals are deliberately sticking thin plastic sheets into card slots to cause the next real inserted card to get jammed (this is in fact one of many reasons why legit users should avoid the motorised card slots in the first place). But if you cause things to jam up, you could get treated like a criminal (camera → facial recognition.. etc).
Maybe loyalty cards.. grab a stack of loyalty cards from a grocery store and use those as dummy cards. Better ideas?
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:
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).