danimal, you need a clue. Their statement was correct, walmart sells Vizio, but it's not their brand. It's a true statement, as true as 'walmart sells sony, but it's not their brand'. Costco also sells vizio. Amazon, compusa, and buy.com also carry vizio.
Vizio is a more price-conscious brand that targeted mass-market resellers (not necessarily big box stores, as it were, but VERY big box stores, so Costco or Walmart vs Best Buy, and online retailers.
They started out very low cost, but their quality is improving. After all, they put VERY little into advertising, so their margins, while slimmer, has less going toward those type of costs, and more to making a good product. Are they a Sony? No, but I've heard good things about them for some time. You'll note they tend to rate well on Amazon, for instance.
They're just relatively stable. As for why there are units being returned at Costco? It's because they basically own Costco's LCD HDTV sales, and that is their single largest retail channel. So, largest retail channel of the largest seller in the US... yeah, that's where you'll see them.
But no, calling them a walmart brand, and then chiding another person with "get a clue", only shows militant ignorance on your part.