Why do HD TV's look so awful with standard TV in the shops?

Hi everyone, I've been on the verge of buying a flat panel TV for some time but everytime I think I've seen the ideal model for me, a quick trip to the high street always leaves me disappointed. HD sets look great showing DVD (or increasingly BR/HD-DVD) demos but tuned to standard freeview they often look terrible. Reading reviews it seems that most TV's require some tweaking but you would think that the shops (even prestigious dept stores like John lewis) would do this to show them off well? Even some Award Winners have looked pretty bad on standard def broadcasts which I guess, is what we still end up watching a lot of. Am I reading too much into these displays which haven't been set up properly? I like the spec of the new D3000 Sony range and the Sony W2000 but they don't look great with SD off air broadcasts in store. Are they better with some tweaking? My current CRT TV is a much sharper image and it's making me delay and delay and delay again! I'm now thinking of looking at the Panasonic TV's reviewed last month as they seemed to offer good SD performance as well as HD. Thanks for the great reviews, Phil