[Galaxy Tab 7.7 General] EarlZ:
I've had mine for almost a month, no burn-in issues, Ive been using the Tab almost in portrait mode and stopped using Honeybar just to see how fast the burn-in kicks in, nothing what so ever.

I cant judge if its visible in normal use or not, unlike others I dont assume how a screen issue looks like unless I've seen it or at least pictures of the issue, this has always been the source of many arguments in forums, people just assume all screens are created equally and just because they dont see the exact same issue on their end they actually become more aggressive and hateful and they tend to find the need to keep defending the product. What gives?

Companies always add a cost buffer to cover for returns and that is usually with upto 3 returns, but complacent people just accepting obivous defects are also the cause for this level of quality control since Samsung can now get away with it, especially that some people are false advocating that there are issues thats normal to AMOLED which is incorrect.

I havent used my Tab yet as an ebook reader so Im not exactly sure what they are experiencing but the pictures posted paint a clear picture, It can be annoying at times I suppose and when a product is marketed for its great screen and deep black levels, should anything less be expected? I mean personally coming from a Galaxy S which had none of the screen issues you've mentioned, the Tab7.7's screen should be expected to be better in every single aspect, right?

I've been quite active in this forum and I haven't seen anyone report multiple exchanges yet, I didnt even exchange my Tab yet.

I dont know who you are specifically referring to but I also use greys as my test images, let me give you a little more perspective incase you made a 'selective reading' in regards to this issue.

Grey colors easily allow you to check if your getting a quality screen or not, they can easily show those lines and discolorations with out the need for using multiple test images, they give you objective results especially when your buying the device but its not very conclusive since the store light will show a lot of reflection on the screen.

Testing at 0% brightness in low light environment is also ideal for an objective testing to avoid any reflections that you might see hiding these flaws, but if one exclusively uses the device in a very bright environment then this step can be skipped.

And this is the real world perspective:

This is the original grey image:

and it should look close to that on the tablet.. For comparison, on my Galaxy S and my former Galaxy S2 can render this color perfectly.

not something like this:

one side is darker, visible lines, dots, circle marks.

You can argue that it only affects greys but it does affect a lot of things you see on the screen and to a certain extent like this:

and when we flip the tab over we get this:

Ignore the moire, notice that one side is darker than the other.

This is how the original frame looks like:

Sure not everyone uses the Tab7.7 as a media player, remember those visible rings and spots above? Check out the attached images.

This is because reviewers hype up the black levels saying its totally black and some internet articles say that AMOLED is in an 'off' state when displaying blacks which gives us the false information and relatively ruining expectations, my first samoled device was the S8500 (Wave) and the blacks were great, no blobs or spots and it had a very faint glow, that was the foundation of my expectation which was further reinforced by the Galaxy S that gave the same results. Others may have started with the Galaxy S2 and the expectations set by reviewers so they ended up returning their devices. On my end I returned it for the yellow tint, which the technician also confirmed that it was very visible and during that time there was nothing they can do.

Sorry for the wall of text but I felt that I should be explain this thoroughly as I am very affected by the screen issues and I am very vocal about it and it did get things done on my end.

TL;DR

Bottom line is, its a $700 device with its primary feature as the screen which is advertized,marketed and specified to have the most vivid, crisp, sharp and clear images. Others are reporting that they dont have any screen issues-what-so ever so why should someone else for settle anything less?