Walmart, Kmart & Target make up the three corners of a LEGO Bermuda Triangle. Sets will disappear off of the shelves (often without ever having been clearanced). Sometimes those sets re-emerge weeks, months or even years later!
Here are a few recent examples...
About a month ago, one Walmart put two Aquaraiders sets out (not on clearance). They did clearance them down about 50% within about two weeks. Some older Spongebob sets, a few Creator mini trains have also appeared within the last two months (at different times).
On Sunday, at another Walmart they must have done inventory and the following sets all re-appeared: Bioncle set from 2006, Police Pontoon Plane, Troll Warships, Dwarves' Mines, Axalara T9s and several Agents sets. All were in varying stages of clearance.
That same day, a Kmart had a few Mars Mission sets.
Yesterday, I went to Target...and found a Creator Sub from 2005 just sitting on the shelf. I scanned a few UPCs of some sets I was looking for and found they had been removed from the system completely, but the Sub was in there for full price!
It gets stranger and stranger all the time.