Unless it's a crappy microSD card, in which case attempting to read a bad sector will cause the card to stop responding. Actually that's not quite what happens - it does return an error, but then doesn't respond to any further reads. Okay, that's mildly annoying but I can deal with it.
Unless it's a really crappy microSD card, in which case most of the time it won't bother with any kind of error but will just return garbage. And not consistent garbage, but different garbage whenever you try to read that sector.
Unless it's a really really crappy microSD card, in which case it's not just one bad sector, but about 100MB that's now effectively gone. Except because the card doesn't bother with actual errors, you don't know which 100MB is gone.