Depends on the type of usage you give them. For a casual user, that likes to unplug them without stopping the device, if the OS hasn't finished writing the information to the drive, and updating the table, you a get a corrupt table.
If you let it sit until its done and properly stop the device, you reduce the corruptions to a minimum.
Other times its the interface itself, if something happens to it like it got snagged when writing. Or the drive was abruptly moved it can cause writing problems.
Power variations can be very damaging. If you don't have the drive plugged into a regulator.
I'm not saying all these things will invariably cause corruption, but it should be take into account that all electronic equipment is bound to fail at some point. USB drives are just more susceptible to writing failures due to their very nature. However if you make sure to stop the device before unplugging it. Have a constant flow of electricity, and keep it from shaking or moving abruptly you can minimize the risk .
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Ignorance is not necessarily Bliss, case in point:
Unknown has caused an Unknown Error on Unknown and must be shutdown to prevent damage to Unknown.