What a local Wal-Mart did a few weeks ago...
It's, in my mind, a relative of "bait and switch". They had a hanging shelf on an end of an isle packed up with Great Value (Wal-Mart brand) parmesan cheese. Then a day or two later it was all switched out with the more expensive Kraft brand. Praying upon people's stupidity.
And before anybody wants to claim it was overstock they were putting else where, no -- they removed all the containers from the shelf on the isle, to put it on the display, leaving a big empty whole on the shelf.
Some asshat did this on purpose.
A few months ago I caught another one at the same store: the Chips Ahoy! cookies were lowered down from about $2.50 a package to like a $1.50 to $20.00. For mere days, then raised back up. My speculation: Hoping people wouldn't check the price again and assume it was still lower, 'cause most people either don't look at the price rung up or if it's not what they thought it was, they'll most times take it anyway.