I do know what a good TV picture should look like - I was trained to set up analogue monitors (although it's definitely not something I enjoy doing!!!).
At the time we were shopping (3 years ago), the plasmas we looked at were unpleasant in comparison to the Toshiba, which was by no means the cheapest in its class. We bought smaller than we could afford (40"), because it and the Sony Bravia both stood out as having better rendered pictures.
It's not just contrast. Other factors in play include: colour rendition, motion artefacts, compression artefacts, etc. As I said, the tricky thing is decoding and rendering a low-bandwidth source, like a commercial Freeview MUX. Most of the 'brassier' contenders did a pretty poor job of that.
It has to be said, too, that most broadcast TV's technical quality these days is dreadful in comparison to analogue PAL I of 25 years ago. There are notable exceptions, and I've noticed a distinct improvement over the last few years, but when DVB-T was introduced, it was horrible.
The best stuff one sees these days seems to be down-converted HD. To my eye, it's often far better than stuff originated in standard definition. I've got a Canon XL-series standard def camera, which looks dreadful next to a Sony Z1's standard-def output. To be fair, it's far easier to expose properly, focus etc. on the Sony, but that's not entirely it.
There's also a HUGE difference in the quality of LCD units too. I'm writing this at a Sony 19" panel, but there's an LG 17" right next to it, with the desktop spread across both. I can't get the colourimetry even close on the two of them. The Sony is more subtle, the colours are more correct (I've proven this experimentally), and the contrast range is smoother. The Sony also has far better blacks.
I do a lot of stills photography, and now wouldn't dare risk post-processing on either the LG or my HP laptop (arguably even worse than the LG!). It's the difference between, say, Canaletto and Warhol!
I'd reiterate: test them in the shop on a Freeview source. The ones that do that well, will most probably do everything else well too. An HD recorded source, such as BluRay, is an easy win for the salespeople and the TV manufacturers.
And yes, they're all c**p compared to a grade one hi-def cathode ray tube.
Cheers, E. (Luddite, me?)
PS: There are rumours that the manufacturers have lobbied against the reintroduction of the test card. Carol Hersee has got them worried!
