Got mine couple years ago as a floor model. It sat on the showroom floor with full brightness and contrast, running the demo mode over and over. Talk about IR! It was terrible.
Fortunately, the salesperson was cooperative and let me put it in screen wipe mode overnight. When I returned the next day, the IR seemed noticeably lighter. Based on that progress I went ahead and bought the unit at a discount. I obtained the WOW disk and ran pixel fix overnight the first few nights (and days). Finally, the image was only barely discernable in skies and solid scenes. That was two years ago. Now, the picture is awesome! No IR except the occasional ghosting others have mentioned. Definitely no burn-in.
I'm not looking forward to trying to replace this set. I'm afraid everything else will be a step backward. OLED, anyone?