Best Buy's TVs are:
a) abused (stuff like burn-in occurs often at BB)
b) have terrible settings
c) have terrible sources
With some work and a decent source setup properly, connected to your TV in the best possible way, HDTV can be awesome. The workers at Best Buy pretty much use the price tags to tell them which TVs are better than others and then read off the info card in front of the TV when a customer asks them for details about a set.
www.avsforum.com if you really wanna learn about this kinda stuff. Be prepared to put in alot of time reading before you become even semi-knowledgable.
If you wanna see some nice HDTV setups, find a smaller (and usually extremely expensive) electronics shop that looks very high end (not a chain, or at least not a big chain). These places will likely have the TVs setup closer to properly.