What term is used when someone imposes his or her own meanings and prejudices onto the 'art' of another culture?
The word that you may be looking for is ethnocentric critique.
Ethnocentrism is a behavioral tendency explored in the field of social sciences where the individuals place a higher value and give more power to their own culture, thus considering themselves superior to others as members of their particular ethnic group.
An example of ethnocentric behavior is religion. When members of a specific cult or religion feel that they are God's "chosen ones" they will automatically criticize, judge, and expect less of others based on the sense of over-importance that they give themselves.
In Art, an example of ethnocentric criticism could be the cause for the controversy regarding Picasso's Les Demoiselles (1907). There are plenty works of art depicting naked women and courtesans. Yet, these demoiselles featured African tribal masks which may have shaken the latent feelings of ethnocentric bias in some critics. Even if this were the case, how is it possible to categorize art as "controversial" if each art movement follows its own aesthetic rules? Could it be that the "controversy" behind some works of art does not have to do with the application of the artistic licence, but on the bias against anything that goes against the status quo?
The result of ethnocentrism in art critique is that all the criticism will be biased and flawed; the critic observes art from an ethnic, cultural, or racial perspective rather than from the aesthetic principles that each branch of the Arts represent. Art is not to be used to moralize, teach, or judge; it is not a product of analysis, morality or immorality. In Walter Pater's words
L'art por l'art: Art for Art's sake.
And in the words of Pater's favorite pupil, Oscar Wilde against the use of art for judging cultural differences, morality or immorality,
Art is Quite Useless.