I have visited Poland twice in recent years and always had good experiences. On the first visit I was using a contactless card and was never offered DCC. All transactions charged in PLN. Second time with a chipped card but no contactless. After a few odd looks from cashiers (contactless and EMV were introduced at the same time in Poland, so all their cards are contactless if they have a chip) I was only ever offered DCC in Carrefour. The machine had the confusing press Cancel to charge in PLN type of system. But at least this message appeared in English automatically. Nowhere else, including transport and hotels, were I offered DCC.