There may be nightmare restoration cases, but there are also ones that refuse to die.
I got one at the ETF some years back for 20$ that was beat to heck, had to have it's CRT rejuvenated back from the dead, and a new audio output tube popped in to replace the missing one. After that, with all original parts except for around 5 of it's original paper caps replaced with maroon drops from a ~60's repair and several tubes that had been replaced way back, I brought it up on a variac. Once I got the voltage up high enough I was greeted with this....
Even in sad cosmetic shape from a hard life, and with nearly all of the original parts still installed that old trooper still could muster a picture and sound about as good as when it rolled off the line....Now THAT is build quality!