Ok, I've been running my TCP50ST50 since Monday, using the slides to prep (ok, and I admit to sneaking a few peeks at programming during that time too).
I think the faint line on the right side is probably a result of the design or manufacturing process, because I believe I have it too and it seems too common to be a defect. It is so faint, though, that I wasn't really sure I was even seeing it until coming here and seeing the other posts about it. It could be that some sets have it worse than others. I think probably all of these sets have it but on some, it's just so faint that the owner doesn't see it. I don't see it at all during programming, and only so slightly on some of the slides that I sometimes think it's the result of an afterimage of my eyes shifting slightly as I'm looking at the TV. I am super-critical of stuff like this too - in fact, I bought this TV partly because my old 42" LCD has a really noticeable (to me) line right through the middle!
Here's my thought on that, though. Like it or not, there's no such thing as a perfect TV. Every year TV's get better, but that doesn't mean *all* the annoyances will get worked out completely or that a few new ones won't crop up, especially in a mid-range TV! (Otherwise, why would anybody spend more?) Instead, we get incremental overall improvements, with each TV still having positives and a few negatives. Hopefully, the positives (vastly) outweigh the negatives, but I think they do with this set.
Frankly I think we're all a little bit spoiled these days. Even just a few years ago, I felt like I got a steal with my 1080p 42" LCD for $1,500. Nowadays, that would be a low end set that would sell for more like $500, and today's model would have better black levels and contrast. A similar thing is true for PDP's - the ST50 series has amazing picture quality for not much money relatively speaking, it has some clear improvements over the ST30's, and the panels are insanely thin and light compared to what PDP's were like even just in 2010. But still we complain about a faint vertical line way on the side that some of us can't even see.
If this is the one criticism of this TV that I end up having, I will be extremely happy with my purchase. Like I said, my old LCD - which cost more money and has a smaller screen with less contrast and a much worse black level - actually has *three* distinct lines where the individual panels that make up the screen line up. So in any case, the ST50 is still a vast improvement, and *plus* I have all the other advantages in picture quality that the ST50 has, some of which are unique to the ST line and above, and to Panasonic (hard to find better black level at this price, for example).
One thing I have noticed as I've snuck a peak at some programming, though, is that I do notice a yellow cast on the normal custom settings (I've dialed contrast back to 50 and turned off all the picture enhancements on the HDMI input, but have otherwise left the colors alone). I'm hoping that once the panel prep is done and I'm able to apply D-Nice's settings, that goes away. Otherwise I'll try a calibration disc.