YES you can get your set calibrated to get a lot better picture, and it wont matter as long as you are being sent garbage to watch.
HDTV has a built in advantage over ntsc, doesnt rely as much on broadcasters, its mainly a digital feed, but you will get a lot of junk.
The most basic thing you can do is turn your tv off of "torch mode", new sets arent affected as much as crts were but too bright a picture will wash out detail.
And theres a new thing, the "backlight" control, this can increase the apparent black
level in some lcds, Dlps and sxrds, and "microprojectors" sometimes have an iris
that does the same thing, I run mine at 60% sometimes.
If you are a tweaker or a tech you might like isf, some dont care.
Sets these days deliver a pretty fantastic picture out of the box, I'm not even getting as much "red push" as I used to.
I used to "do electronics" so I can usually get a set pretty close just eyeballing the thing,
to each his own I guess, sure these guys use instruments but some things wind up a judgment sometimes between what the calibration tech does and what you like.
Myself I have never noticed much difference in adjusting certain parameters, most people dont notice, thats why manufacturers dont bother, its not worth the money to them, and these are the guys who set every tv in the world to full brightness coming out of the factory,
both to sell sets and to wear them out faster