After the clarification, I'm still not sure what the effect referred to is. If you search "creaming" in tea literature, you could find a bunch of articles talking about the creaming effect in (mostly) black tea when there is NO milk or other things added.
In Chinese tea literature, there are some research about association of creaming effect (indicating richer inner content) and the tea (mostly black tea and shu puerh) being of high quality. But in most discussions, people would point out that creaming may or may not indicate high quality and there is no absolute association.
In English-language tea literature dealing with creaming effects, most articles I've seen focus on creaming effects caused by low quality water and avoiding creaming effects for black tea (especially ice tea). In the latter case, having clear liquor (because people like it) is the main concern, and the quality of tea is not.