Micro SDHC card - Incompatible medium detected

In checking through some of my MicroSDHC cards, FreeBSD reports
Incompatible medium detected

Can anyone explain this? Is there a chance of recovering something from this card? Could it be dirty? Other cards have resulted in 'No medium present' ! This is kind of worrying if I have a 64GB card which may have had 30,000 of photographs on it!!!
Maybe it was since I can't reproduce the error, or maybe card wasn't inserted fully.

I do have two cards which simply can't be read - I get medium not present - tried them in all sorts of readers... I just wondered if there is any way to tell that a card might be about to fail, ie something like a disk scan for SDHC cards...