I've never had the ol' 'No game in case' trick, but when I bought The Sims on PlayStation2 (don't ask, really), I came home to discover a WONDERFUL copy of Sim City 2000 in there, for the PC. MMMM.
But I bought it from K-Mart, where they love to tear the shrink-wrap off, throw the discs under the counter, and sell you game boxes that have been picked up by hundreds of fat sweaty kids that have a saliva problem.
Just goes to show, you shouldn't hire old ladies and toss them into the audio-visual department.
"YOU WANT A X-GAME STATION 2 SONNY JIM? MMMMM, I'M ONE HUNDRED AND FOURTY YEARS OLD"