You should not expect such cards to be reliable.
The reason this is possible is because of the way flash memory is manufactured now: the chips are produced with faults, then connected to a microprocessor that runs sophisticated proprietary algorithms to identify the faulty memory cells and reliably distribute stored files across the working memory cells, and also report to both the manufacturer and consumer the total capacity of those working cells. This way a single silicon wafer produced with imperfections can yield hundreds of sd cards ranging from megabytes to 128gb each.
The scammers you're talking about reprogram the microprocessors on these cards to identify themselves as having a larger capacity, but this isn't so simple as it being connected to a reliable 4GB flash memory chip and reporting itself as connected to a reliable 8GB flash memory chip, rather they're all uniformly connected to highly unreliable 32GB or greater memory chips and correcting the reliability problem in firmware, and there's no telling how the scammers messed with that besides the change in the reported capacity. I would expect any file saved on such a card to have pieces randomized or zeroed over time.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.