Well, objectively, you can't have an art museum that has only beautiful art in it, since beauty in art is subjective and non quantifiable, so yes there can not be an art museum that has only beautiful paintings, and the beautiful paintings that supposedly are there might only beautiful to the eye of the curator.

Either way, the point is not wether or not you can have a place with discourse with the all good qualities described, it is more so that because those qualities are not quantifiable, it is impossible to know for sure.