Funny thing, almost the opposite happened to me when we first came to Tourist Central. Sat down at a bar at Ground Zero, ordered a caña, and was brought a litre bucket. Not what you want when it's 40° in the shade. When the waiter insisted what I had was a caña, I pointed to my partner's Coke in a standard tube glass and said "No, that's a caña". He said "we don't do beer in them", so we walked. Simples!
The other trick is to advertise beer at €1, but bring a bottle instead of draught beer and when the bill is €1.50 and the punter points to the sign, to say "oh, we don't have any draught today and bottles are €1.50"
Now we avoid that bar and all those around it, where Brits can be seen mid-December in their undies, stretching out and facing the sun with their eyes closed as if meditating, presumably happy to be fleeced just for the opportunity to sit in the centre of things, 100 metres from other perfectly good bars serving locals at normal prices. Same all over the world, I imagine.