The only bright white text channel logo I have noticed so far is on Encore movies...
The ESPN logo in the lower right corner of the bottom line.
Combination of the Encore HD logo (from a SINGLE MOVIE ), AND the ESPN 2 logo (from Mike & Mike), created a mash-up on our ST50 that has remained stubborn as all get-out.
After several weeks, including 2 weeks of Very Careful Babying, the other Persistent Images we had - Uverse "GUIDE," and the "M" from the Uverse time display (up whenever the Guide is) - have All-But-Disappeared, although the area where the "Guide" heading shows up seems fussy.
The Encore/ESPN mash-up is MOSTLY gone, but it can STILL be made out, however faintly, on many advertisements that feature a largely white or light-colored background. Frankly, most people would not notice it even then: I, of course, happen to KNOW where it was / is....
To be fair, this panel does seem to have grown a BIT less prone to Quick Onset, Medium (or longer....) Duration IR, as compared to, say, roughly the 250 - 400 hour usage period.
Currently, Quick Onset IR (that is, IR from images that are NOT on the screen for an extended time period), appears to have reverted NEARLY to the "Short Duration" variety that we are accustomed to on our other plasma sets.
Am hoping that this trend will continue as the panel further ages - but am still taking precautions, just in case....