A common thing here, too. Going out of business sales are the worst. It used to be that retailers sold most of their goods in a lingering going out of business sale. What would happen is the good stuff would sell high, but by the time you got to the end, the junk that was left was 10% of new.
Now, stores take a payment as they're going out from firms that specialize in those sales, and what happens is the high value goods are generally removed from the shelves and sold to another retailer. The resale firm comes in with old stock that never sold or less desirable items and then puts "marked down" prices on it - essentially trying to catch people who don't think very hard so they can sell stuff that nobody wanted (like year old computers, older model TVs, etc).
I'm sure amazon facilitates this further now, along with ebay, where large volume sellers can get lower commissions. If you have something like a desirable TV or computer, there's no reason to sell it for 25% off when you can buy the stock in a negotiate deal and go sell it 2% lower than the going rate on amazon and do a lot better.
Wal mart does a little finagling, too, by making clearance racks and non clearance items mixed with them without demarcation of anything, and they used to have a price match policy, but that doesn't apply to most things now including the mix in items on clearance or price matched bits. They're very clever - but their policy is written - most people just don't read it - the way they lay the aisles it can be like a schematic and they will flatly tell you: on the ends of ailes in section ___ , items qualify for the price match guarantee, but the items between two guarantee price displays are not subject to the same pricing terms.