The difference is that I don't spend my time in front of the TV watching Blu-rays, or even HiDef broadcast. I judge a picture by the continuity of tone from black to white, and natural skin tones, and honestly it's good enough for general telly. Of course, I am (when I do) viewing a 32" screen from ten or twelve feet - if you are a videophile and like to sit close enough to see individual pixels, your requirements are probably different.
I might one day see what "calibration" does, but I lost interest when I discovered I can't tell what panel I have. The problem is that such judgement is highly subjective, and unless one could alternate between "before" and "after" it might be difficult to know what the difference really is - psychologically one will be expecting to see an improvement, and therefore convince oneself one does.
Call me undemanding if you like, but I would not accept colour casts or unreal contrasts. Bear in mind also I am in the UK, which might make a difference.