We were in a town in the mountains in Spain, Arnedillo, that has hot springs which emerge in the river bed
Its quite touristy, unlike most places round here.
We peered into a restaurant nearby and saw people having very decent food, went in and ordered from the 'menu' which confusingly means the set menu, 'carta' means the a la carte. Remember that because it will matter. We ordered without saying more than the words on the short menu del dia.
My starter was a tiny salad and my wife's was a doll's portion of paella, followed by a main course of miniscule amounts of some meat. At which point I had had enough and said to the waiter that I was not happy. He explained that we were having the set menu and everybody else was on the a la carte. What was funny was his mounting horror as I said in my decent Spanish 'So whole tables are ordering the only two things that are on the set menu as starters and then the same main course. What a coincidence .' My voice is as loud as my shirts.
The panicking owners came over. Their version of events was that all the other people were residents which is why their meals were better. 'I'll ask them' so I went round all the tables asking very politely if they were having the menu and if they were staying there. They were all having the menu and not staying there. Voices were raised 'Why aren't you feeding these people properly? Have you no shame? You thought they wouldn't be able to complain, give them an hoja de reclamacion (complaint sheet)!'
I asked for the complaint sheets, one copy for me, one for them and one for consumer affairs. These are numbered so they can't accidentally lose the one they have to send to consumers.
They didn't want this to happen, so we were offered any sweet we wanted, free coffee and a brandy. A wag in the restaurant shouted 'Make them large ones, if I were you! Not tourist size!'
I suppose it happens everywhere, to some extent. You hear of places with tourist prices and local prices, and it happens here with drinks and decent tapas, but not usually so blatantly.