I wouldn't worry about the hotel. You may well be 'offered' DCC, but as long as you make it clear you want to pay in EUR the staff are unlikely to try and trick you. If for some reason the transaction goes awry, someone -- the receptionist you're dealing with or their manager -- will know how to void the transaction.

Restaurants can be trickier because -- as islandguy84 wrote -- many servers hold on to the POS terminal. (With contactless, as long as there's no DCC involved, that's actually the most efficient way to do things -- as long as you can see the amount before holding your card up.) And sometimes, when you are put in charge, the second question catches you out.

Disputing a charge and getting it voided is typically harder in a busy restaurant/bar environment (and doesn't become easier if you've had a glass or two of wine). For a dollar or two, with friends waiting, I'm not going to make a massive fuss -- just make my position clear, take my printed receipts and dispute the mark-up later.

To put the above in context: I've used a USD Visa card almost 30 times since arriving in Portugal and only had three DCC issues. One was a hurried server, one was me misreading the second DCC question, one was a hotel receptionist pushing buttons while dreaming. Of the three, one was voided immediately. Chase instantly refunded my DCC loss on the second and I'll dispute the third once it moves from "pending".

Card issuers and the phone giants should indeed be blocking this.