I've had my rMBP a couple weeks and never noticed any ghosting. Have an LG display. Today I noticed some image retention on this background color:
http://www.historum.com/
I've never noticed it anywhere else before. Do they all do this?
I'm beginning to think all the LG panels do [or will eventually]. This is my 3rd (1st had image retention; 2nd had giant dent in the screen), and I inspected it VERY closely at the Apple store and for the first week afterward. It has now developed image retention over time. It's an LG panel. But, it's not too bad at the moment (I really have to look for it), and it seems like getting another panel would have a higher probability of not pleasing me than keeping this one, so I'm going to stick with what I have.
Besides, it's got a 1 year warranty, so if it develops into something really bad I'll swap it out then.
But I will say -- as soon as they come out with a retina OLED screen -- I'm snatching that sucker up.