They’re almost definitely real. They’re paper cards that have been used in the casino and then marked - either they have a corner chopped off or a hole drilled through the deck. They’re perfect for kids playing go fish, but nothing you’d want to use in a real game.
Somebody was auctioning a lot of these here, within the last month or two, and shockingly we all behaved and did not crap on his thread. But yes, they’re sold at dollar stores because they’re practically worthless despite being beautiful, good-quality paper cards.