Q: I bought three containers of cottage cheese before the “sell by” date. They sat in my fridge for almost a week, and when I opened them, they were spoiled. Am I entitled to exchange them?
A: If you kept the cottage cheese containers in proper refrigerated conditions and they spoiled before the “sell by” date, you can exchange them, since they were clearly defective. If you discovered that they were spoiled shortly after the date, it depends on how badly spoiled they were. If they were badly spoiled, they must have already begun to spoil when you bought them, so you can still exchange them (C.M. 232:16).
However, if they are only slightly spoiled, the seller is not obligated to exchange them, since the cottage cheese may have still been fresh when sold and only spoiled in your fridge. Since the defect was first discovered when the products were in your possession, the burden of the proof is on you, as the seller is in possession of the money and we assume that they spoiled here (230:7; 232: 11, see also Sm’a 232:35).
Despite this, some stores allow you to exchange spoiled merchandise with no questions asked and just require the sales receipt.