Is there really such a thing as a white LED? The ones I have seen have all
been red/green/blue LEDS on the same substrate to produce what appears to
the eye as a white beam, most of which are far too blue for my taste.

Have you never seen the ones that use a blue LED and a yellow-fluorescent
pigment?


They are blue because blue LEDs have a much shorter life than red and
green
so the color will change as they age, and they start out blue before the
end up
a red green mix (yellow/orange).

What?

I have never seen a dead LED (though I assume they exist), nor have I heard
of LEDs becoming dimmer with age.


That may be a different story because PAL TV sets never had them. NTSC
sets needed them because the phase of the color carrier wandered and
often shifted to the green, while PAL sets reset the phase each line and
therefore were always "correct".

NTSC does not, and never had, an inherent problem with phase stability.


I have yet to be impressed by an LCD/PLASMA TV. Every single one of them
I have seen is oversaturated and too bright.

Because you're seeing them in "torch" mode. There are plenty of good sets
out there. Find a dealer with a Pioneer plasma set, have him put on a really
good disk, and be prepared to die.