Something similar happened to us. I think I mentioned it before.Myself and a colleague arrived at a hotel in Dussledorf quite late and the restaurant was closed. However, we noticed that there was a buffet on the next floor down so we got into that. A waiter came around and we asked him for a couple of beers. He went off and spoke to a guy who came over to us to explain that we were at a private party and whilst they didn't object to feeding us for free they were not going to stand for our beer!
We were on a guided long weekend trip to Amsterdam, and the lodgings were in one of those ubiquitous “tourist hotels.”
Breakfast was included, but being Americans, we didn’t know that there were different levels of breakfast, depending on what each tour had cost.
We were on the bottom rung, just bread, cheese, lunch meats, but on the way down, we say this other room filled with all that and pastries and cereals and cooked-to-order eggs, so we just figured, “This must be where breakfast is,” and wandered in there.