As a child I joined a guided tour in a small provincial museum. A staff member praised the mingle-mangle of the collection. He was really proud of his museum, especially the portrait gallery.
As far as for him it was, piece by piece, top works of mythical dimensions. However, at almost any portrait he claimed that the evidence of the exceptional skill of the painter was to be seen in the eyes. Wherever you stood in the hall, the portrait always looked at you. From the left or the right, it did not matter. It was nothing short of genius he said, and the group to which I belonged agreed with him: Masterpieces.
Enthusiastic ignorance because it is pure nonsense. When a portrait looks straight at you it does that from every different angle. And if it looks cross-eyed as you stand straight opposite, it does so if you stand diagonally.
After all those years I don´t remember one single painting but I do remember the guide.