Before I make any purchase I typically do somewhat extensive research on the product, whether TVs, car tires, meat thermometers, etc. I'd bet a Google question like "Best size TV for 3D would have generated a lot of info. As much as I let my two son's be responsible for their own decisions, I take an interest in what they might buy, then I do research like I'm buying it myself, then I can have a half-way intelligent discussion with the kids about their purchase.
I just saw my son's new PS3 3D TV thats like 20-somethin inch TV and I was not impressed. Why would Sony offer such a TV for a gamesystem that is less than 30 inches. Im pissed I had to pay for it this nonsense out of my own pocket.
BTW, i gave my credit card to my son and let him buy anything under 500, and the ps3 3D TV was what he got.