You don't shop much, do you, Mr. Happy? Otherwise, you'd know that at this time of year, retailers are getting rid of the merchandise that they couldn't sell for Christmas.

Contrary to what you think, most retailers have a fairly strict formula for pricing items that includes the price they pay for an item, an increment that covers their expenses, and then their "profit" or "mark-up", which really is the money that they get to keep, or that they divide with their sales people(a surprising number of people still work for commissions)--

After Christmas, they've given up their "mark-up", and are just trying to empty the shelves and recover their investment so they can buy new merchandise for the next season. That's what's called a "clearance" sale. Usually, this "sale" includes the seasonal stock only, and the regular store merchandise isn't effected(that's where the "The sign said this was 50% off" fights at the register come in)

There are other kinds of sales--"loss leaders" where the merchant decides to offer some merchandise at or below his wholesale cost to bring you into the store, hoping you'll buy something else, and "specials" where the prices are lower because the supplier has provided the merchandise at a reduced price--Legally, retailers must be careful
in promoting "specials", because if they haven't actually sold the same products recently for a higher price, they often can't claim the items are being discounted--

And, again, Mr. Happy, the folks who do the shopping know all this already.