Oh, bull. The dollars are the bottom line. If you sell enough units, your profit soars, and the returns don't hurt your overall bottom line.
Costco sells tons of Samsung and Vizio products, and, most of their customers are happy with most of their products.
Otherwise, Samsung and Vizio wouldn't be selling their stuff through Costco, if they are loosing money, for such a long period of time. If you can produce large numbers of product, you can sell it at a reduced margin, and bank the dollars, not the percentage, ala oil companies.
Also, some products need to be moved, or they devalue. Costco is great for that, for big companies.
On the otherhand, one might argue that Panasonic is dumping some LED TV's cheap, that are pretty bad, at Costco, for a great price. If they fit what you want, probably a 10 bit screen, 720p, analog and HDMI inputs, with some screwy software, they are a great deal.
So, to go around one more time: Costco's return policy is vital, since, as some have pointed out, the worst products are dumped there, by companies, for little money.
Without that return policy, people wouldn't be tempted to try stuff that they would otherwise be totally screwed with, if they bought it somewhere else.
So, since I've been a Costco member, Premium, from 1993, and I spend a LOT of money there, I don't in the least feel like I'm screwing anyone when I return a product.
Their business is built on customer satisfaction, and, it works. I spend a huge amount of the money I earn there, since they provide great value in the stuff they offer.
If you spend 15 grand a year there, and you return a couple defective products, I don't feel real guilty, and, in the long run, they have a loyal customer.