The honest to God truth is set up all sets equally running the same source media with the same picture settings etc etc and you'll be hard pressed to tell the difference...
exactly.
in-store the sinotec feed looks chit - but im pretty damn sure that my HDMI connected Set at home, running a blu-ray source, looks just as good as the 18k "Big brand" sets on display at these stores, which they use "Awesome videos of slow-motion butterflies flapping in front of a waterfall" in 1080p DEMO Discs.
the expensive Sources are recorded in the amazon or something using freaken Imax-like camera's, and are only allowed to be shown on the say, "sony set" because it's the sony demo disc, and they paid for it.
meanwhile, the sinotec gets some DVD, via component cable to "show off" it's quality...