Try to check the dates on the yellow stickers, some stores can be very slow at removing old offers even though the yellow sticker is still up.I haven't noticed and - when it comes to Tesco at least - I keep an eye on them. It's amazing how many errors you can find on the receipt; usually an offer that 'didn't go through'. When I complained, I was told the pricing system was in India or somewhere far-flung. I replied by saying that may well be, but it's strange how the errors always seem to be in Tesco's favour. Check your receipt!
Do their surveys take into account, say if Tesco own brand products are out of stock?
In fairness the CSO never take account of multi-buy offers, only unit pricetag.Back in March multi-buy offers were largely cancelled to discourage stock-piling and panic buying. I am not sure to what extent they have come back.
Our local SuperValu are great for putting up the posters for special offers and labelling the shelves. Not so great at remembering to update the tills to recognise the offer.Bit in general I find Supervalu worse at applying offers - current highly advertised offers especially.