The raw value of the C0 Power-Off Retract Count (Unsafe Shutdown Count) attribute reports the cumulative number of unsafe (unclean) shutdown events over the life of the device.
An unsafe shutdown occurs whenever the device is powered off without STANDBY IMMEDIATE being the last command.
If the drive is operating normally, and other SMART values are within normal values, then the drive should be working correctly.
Common causes for this counter to increase are: Hard power down with the power button, disconnecting from the power source, or any other method that does not use the "Shut Down" sequence in the Operating System; also may be caused by Power supply issues, bad cables, Motherboard/Storage controller issues.
If the counter continuously increases, even if you do a proper shut down, you may consider updating your motherboard BIOS, as well as system drivers. Also, check the configuration in your storage adapter.