I just returned the 50ST50, all their models make a terrible buzzing noise on a lower volume, or if you will be using it as a monitor. FYI.
You do slickdealers a disservice with hyperbole.
I'll counteract your anecdotal story with my own 50GT50 whose 'buzz' requires one to stick their head 6" from the back of the TV to hear anything.
I'm not saying yours doesn't have an issue, but 'ALL'??? Please.