I have a TC-P50S2 since 2010. My first plasma. Ever since powering it up I've seen the phosphor trails.
If some people see it, it's there. Don't dismiss the phosphor lag. Just because YOU can't see it doesn't mean it doesn't exist. For the fact that it DOES exist reduces the quality of ALL display technology that has this problem, IMO. Me, I love the plasma technology theory. But the FACT that it's not displaying images in a PURE fashion really discourages me from recommending plasma technology to anyone. I don't even recommend this to family.
So if you can't see the problem, now YOUR vision needs to be examined. What exactly are YOU seeing? How can YOU see a clear and precise image flowing across the screen when in FACT it's not really cleanly moving across the screen. YOUR eyes are really the problem. You shouldn't condemn us who see it how it is! FLAWED!
This really sticks out with lower quality content. Especially when I watched Sanctuary. It seems more prevalent in 720p or lower quality. 1080i/p content seems hard to find the issue. So it seems, of course, it's something with the timing of the phosphors. Higher content needs faster phosphors. Lower content reduces the display/flicker/Hz/phosphors.
If you want a test DVD to take to stores to see their displays, find a video with a white box that moves left to right. That's it, that's all you need. A white box that moves left to right. Follow your eyes on the box, and you'll see the phosphor lag. My wife says she doesn't see this issue. But when I played a video and told her to watch the box as it moves side to side, she saw it. Maybe that's the wife-factor on HD TV displays? :/
I go to my brother's house who has an LCD display, and his screen just displays better. Movement is more clear, more fluid/sharp. Of course there's no phosphor lag which makes his display better. As long as he doesn't enable that "feature" 240Hz crap that makes it look like a soap opera.
So remember, just because you don't see it doesn't mean it's not there!