Turn the OPC off if you haven't already--OPC is Sharpspeak for the feature that uses a roomlight sensor to turn the backlight up and down in response to ambient light.
To tone down flashighting or clouding--which you're calling "ghosting"--turn the backlight way down and brighten the screen with the contrast control. It's sort of a balancing act between the two controls. LCDs produce black by blocking light, the less light there is to block the more uniform dark screens will look.
Some non-uniformity is almost unavoidable and different people have different levels of tolerance. If you can't get this to your satisfaction try an exchange for one more sample of the same model (assuming you like it other than for this problem). If the second one is no better or worse try some other make/model. Although plasma has some characteristics some find unacceptable they do have far superior screen uniformity.
Finally, copying other's settings is a crapshoot at best. Not only are there variations between different samples of the same model set but different people have different ideas of what constitutes good pq and settings for different room lighting vary widely. There are several calibration discs available, most have voice-over tutorials to achieve the best settings for your particular set.