IPSOS told me a store suspected I was the shopper because I went in with a pen and paper and was taking notes during the shop. I have never brought a pen and paper. I clearly remember the shop and did not have anything of the sort. They told me I can still do the shops, but not that location.
On a side note, one manager flat out asked me if I was the mystery shopper because I asked the same questions about the same phone three months in a row. I looked very confused and told him I did not know what a mystery shopper is. There are two locations that I suspect know who I am. One bends over backwards to give me good service, the other plays along.