YES. It is possible that the card can go from 100% working to 100% bad sectors in a fraction of a second. There can be a number of reasons for this, but the most common reason is ESD. ESD is Electro Static Discharge. In other words, to zap your card: Walk on a synthetic carpet, make sure you wear some synthetic closthes too, then charge yourself with static electricity and finally, when you're charged, touch one of the SD card terminals. You will generate a spark which is more than 2000 volts, most of the time, such sparks are more than 10000 volts. Now, imagine that you zap the chip. If a card does not respond to any input/output at all, all your computer or camera will read is bits that are set to one. Eg. %11111111 for a byte, which translates into 0xff. Since the "bad clusters" are marked using 0xffff, you will see only bad sectors. This indicates that somehow, most likely due to ESD, the card's control-chip has been fried. It could also be due to an over-voltage, such as a 5V on one of the card terminals for a longer period of time.

ESD is the reason for many unexplaniable electronic failures, including your cell-phone suddenly gone dead, you only had it in your pocket (of your synthetic jacket) for 4 minutes.

I recommend everyone to watch these videos, the first is like a 'lightweight intro' (advertisement), but it's very educational anyway:

ESD Intro

The Shocking Truth (1 of 4) (follow its links; I'm only allowed to post 2 links in here)

YES. It is possible that the card can go from 100% working to 100% bad sectors in a fraction of a second. There can be a number of reasons for this, but the most common reason is ESD. ESD is Electro Static Discharge. In other words, to zap your card: Walk on a synthetic carpet, make sure you wear some synthetic closthes too, then charge yourself with static electricity and finally, when you're charged, touch one of the SD card terminals. You will generate a spark which is more than 2000 Volts. Most of the time, such sparks are more than 10000 Volts. Now, imagine that you zap the chip. If a card does not respond to any input/output at all, all your computer or camera will read is bits that are set to one. Eg. %11111111 for a byte, which translates into 0xff. Since the "bad clusters" are marked (in the FAT) using the value 0xffff, you will see only bad sectors. This indicates that somehow, most likely due to ESD, the card's control-chip has been fried. It could also be due to an over-voltage, such as a 5V on one of the card terminals for a longer period of time.

ESD is the reason for many unexplainable electronic failures, including your cell-phone suddenly gone dead, you only had it in your pocket (of your synthetic jacket) for 4 minutes.

I recommend everyone to watch these videos, the first is like a 'lightweight intro' (advertisement), but it's very educational anyway:

ESD Intro

The Shocking Truth (1 of 4) (follow its links; I'm only allowed to post 2 links in here)