ALWAYS CHECK THE SELL BY DATE.
I've been working in the Meat Dept. of my employeer, and I've started to discover that there is just too much meat for us to make sure that anything spoiled comes right off the display case quickly.
As a matter of fact, I pulled about 6 Hams yesterday that had gone bad on the 9th of July. They sat on display until the 27th.
So always check the sell by date, we can only do that so often. (Pretty much all I do for the last three hours of each day is check the cases for sell by dates, giving a discount on items with one day left, and pulling anything past their date.)