I keep an eye out for these things, and I don't think I could pick up on that. The details:
The advice? Use a card with a chip if at all possible - the skimmer just grabs the magnetic swipe data - if you use the chip, it won't get anything.
Walmart last year began asking customers with more secure chip-enabled cards to dip the chip instead of swipe the stripe. Chip-based cards are more expensive and difficult for thieves to counterfeit, and they can help mitigate the threat from most modern card-skimming methods that read the cardholder data in plain text from the card’s magnetic stripe. Those include malicious software at the point-of-sale terminal, as well as physical skimmers placed over card readers at self-checkout lanes.Let's be careful out there.