I could tolerate (stand) yellow and dark cloud on MacBook Pro (use only windows 7). But 4.7" is such a little real estate, 10% of smudge will ruin the whole experiences.
From what people have reported and I read, dark/yellow bands appear at top, bottom or corner. It means the LCD is good but the manufacturing process damaged those area (smudged) when fitting the screen on, being it glue, air leaking (popping sound in one case), or uneven pressure (pressure does change LCD color/lighting a lot).
Someone overseeing the production line should examine some samples and found out why this happened.
What is the most important part and also the most expensive and also most used? the screen. One bad screen can easily kill a company.
Previous LCD was sourced at $99 and now the larger size is around $73. LG LCD is far inferior than Samsung - easily see from their TVs.