Costco's return policy is fantastic, you just have to know how to utilize, and not abuse it. I worked for Costco for 2 years, in electronics sales no less, so I know how it all works. I was that guy who when you returned something mechanical/electronic had to come sign off to make sure you were including everything that came with it, and that the model numbers matched, etc.
When you return anything to Costco, just to make the process easier on them, and on yourself, the product you are returning is "broken." This obviously doesn't apply to clothing returns or anything of that sort. But for electronics, you're much more likely to get hassle about that tv you're returning 1 year later if you're just saying, "Meh, I don't like it anymore" than if you were saying, "The audio crackles, and the colors scramble after it is on for long periods of time."
Make sure you bring back everything that came with it too, including the receipt (makes the process flawless). Manuals aren't as important when returning an item, but they sure are nice to get back. Be sure to include all relevant cord(s), the remote(s), and obviously the main item itself (dvd player, tv, stereo, etc) when making a return. The receipt is important because it displays the item # right away, and they can look it up. It obviously shows your (hopefully) Costco card ID # on it, showing you were the one who made the purchase, but it also protects you from price drops. You can return items to Costco without the receipt, but say that tv you bought was $500, but a year later they had dropped the price to $350. Well, without a receipt, Costco will refund you the last sold price to protect themselves. So even if you did pay $500, you can't exactly prove it without your receipt. Online purchases are different, and they can be looked up per Costco card ID #, so they "should" be able to display what you paid. They of course reimburse the full cost, including item, taxes, and shipping!. All in all, keep those receipts!!
Costco has an implemented system with their manufacturers. Because they buy in such large bulk quantities, they have (with around 90%+ of their manufacturers) a return system where they themselves get reimbursed 100% of what they paid. So don't go hanging that guilt on yourself (or let your wife hang guilt on you!) when you return something to them, whatever it may be, because they are (almost assuredly) getting their money back as well for being such power sellers for their manufacturers.
Just some info for the public! Gotta run, returning my Sceptre 27" lcd from last year's deal, so I can pay $100 more for this 32". >_> My inputs have stopped working (funny enough, they truly have, hah). Too bad I lost my receipt in the move, but I'm taking my chances that my purchase is accessible on the computers!