The Samsung TV we had was the only one actually smart enough to be able to turn on and function as a dumb TV nearly instantly prior to the "Smart TV" functionality booting up. Based on various comments here it seems like not every Samsung TV does this, but the one I had access to (I forget the model number) did do this, which was very nice compared to all the others. On the down side, the Samsung's remote control was downright horrific to use and had these oddly modal states where it expected you to type lots of things in using a T9-style keypad despite the unit also having a qwerty keyboard (which only worked in some modes/apps) on the backside.
Developing apps for these things was enough to get me to decide I'd never buy a "Smart TV" as a consumer. It makes way more sense to get a good "Dumb TV" and enhance it via set-top boxes like consoles (The Wii U is quite a nice media player, if slower than it should be), or Roku or such. Not only is the out of the box experience way better this way, but you can much more easily upgrade the set-top box with new features every one or two years whereas there's very little reason to get a new TV less than once every 5-10 years.