Doubtful that you are truly seeing Phospher lag on the sets. Again, it is your brain telling your eyes something that they are seeing, but in turn, you are trying to tell your brain what you think that it should be seeing.
But yes, overdriving the sets in the stores, or people messing with the settings, and the next guy comes along and used to seeing a calibrated set, or a set that they have adjusted at home to fit their viewing habits, even if they did not go through a full calibration, yes you are going to see issues with the set.
I can see it, when I go to my in-laws, and have to every time fix the settings to get both of their LCD's back into the calibration that I had previously set them at when I was last up there.
I would just go by the best info on the set you are looking at, check it out at various places and if you can, get the settings into some decent recognizable viewing. Worst thing is places like Wal-mart or Target, that have so much lighting, that even if you got the picture decent, it would look like crap in the store, unless you got it home and did the same settings.