1. What I basically did was use a black background and then a white background (Used my ps3/pc to view). You just have to look for a pixel that is different colour from the rest (it could just be a permanent black , it should be very obvious when you are close to the tv.
Example of dead pixel:
http://img444.imageshack.us/img444/4531/dell2407wfpdeadpixeloy0.jpg
Sometimes you can just watch regular tv channel to spot it but if you really want to go all the way try viewing it on these special backgrounds, you will be able to spot any dead pixel immediately with this: (scroll down and click the links)
http://www.gdargaud.net/Hack/DeadPixels.html
If you do have a dead pixel(s) don't panic yet, you can try massaging gently with a cloth, if it still doesn't go away try running something like this:
http://deadpixel.googletoad.com/
If it still doesn't go away or you have several dead pixels then just get the tv exchanged.
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2. Your basically looking for clouding(mura)/backlight bleed. Keep in mind almost all LCD suffer from these issues varying from not very noticeable to unbearable. The w4000 has much less of these problems compared to older lcds but that does not make it 100% free from these. Some users here have reported clouding, backlight bleed which is normal especially in the larger size screens. I myself have noticed some minor clouding and some very little backlight bleed but its not anywhere close to as bad as the examples I will show below.
bad clouding will look like the following:
http://img152.imageshack.us/img152/4381/clouding1mh1.jpg
very bad clouding:
http://img207.imageshack.us/img207/127/sonymesson9te8.jpg
backlight bleed will look like the following:
http://img71.imageshack.us/img71/3671/samsung730bproblempx4.jpg
Also note this will mostly only be obvious during the night with no lights on, or mostly during dark scenes. Also keep in mind these issues may be evident when you first get your tv, but after calibrating (backlight, brightness, etc) can reduce these to negligible levels.
Keep in mind, if you have minor levels and feel like exchanging your screen, you may actually risk getting a worse set with dead pixels, worse clouding/backlight etc. If you have minimal symptoms and no dead pixels then I wouldn't worry about it too much if it doesn't bother you. As I said before this is common to some degree in all LCD's today. If you do not have any clouding, no backlight bleed, no dead pixels then consider yourself lucky which some w4000 owners here have no symptoms.
3. I think what was said best by some users are, do not go looking for these problems as some people (including myself) never noticed some of these issues until they were brought to our attention! However I do think dead pixels are important to look for as those can be quite obvious sometimes.
Hope this helps.
