I bought a new main TV a few months ago and just ordered a smaller one for the bedroom. I never spend money on technology without doing my research but one thing that I have seen in review after review is comments along the lines of "The picture is great because it has a 50,000:1 contrast ratio".
I don't know how manufacturers get away with these claims any more than I know why people believe them. You only have to look at the (black) top of the screen when an extra-wide movie is showing to see these figures are nonsense. And, given that video broadcasts use no more than 8 bits per sub-pixel, the maximum theoretical ratio between white and almost black is 765:1 (and no human can distinguish black from RGB 0,0,1).
Ok, the high contrast figures quoted are usually "dynamic" meaning that the backlight is turned up and down, but this usually results in pretty awful pictures and smart folks turn this down to minimum or completely off. Also, the figures quoted even for dynamic contrast are often impossible too. Nevertheless, even professional reviewers (who should know better) believe and repeat these nonsense figures - what gives?