Sharp Plasma TV "Dark Smudge" Curiosity

[oubukibun]

Hi, guys.

I bought my Sharp Plasma TV about 3 years ago (and it saddens me to hear plasma is a thing of the past, as I agree the image is absolutely preferable to any LCD I've seen), and from the beginning, I've noticed what I consider to be an oddity:

Especially prevalent in pans across rooms or a general area, and NEVER visible when paused or fast forwarding/rewinding still frames, sometimes the image will look as though there are, I don't know how to explain, dark imprints, like a very thin "film" over the image itself that sometimes detracts from the viewing experience. At first, I thought it was film dirt in the films themselves, but once it became a pretty common anomaly, I shucked that thought out. I feel as though I can lift my fingers and pluck these dark smudges/imprints and the picture will look cleaner.... Trying to describe it as best I can for you guys. Haha!

I've never seen it playing my video games, but it is seen readily when I'm watching stuff from my laptop on the screen, and when watching Blu-rays or DVDs. Like I said, it's not terribly awful or life-altering, but I am curious if someone on here can give me its proper name or share a similar experience and if it has any sort of fix, other than to grin and bear it. Heh.

I also have the corners of the telly kind of blackened out, not unlike old-timey portraits, forming borders, but once more, as most of the films I have tend to be 1.85:1 or wider, this doesn't seem to pose much of a problem. Also, these corner-borders are hardly seen when playing my video games. Strange how plasma works, I suppose.

Anyway, apologies for the long post. And thanks in advance to any and all responses!