Hume, Taste and a Debate between a Mother and a Daughter about "crop tops."

One of my students talks about a debate with her mom about fashion and taste in regard to crop tops.  My student, T., suggests that her mom is not in a position to judge the styles accepted by her own generation, even on a Humean account, since such judgment requires comparison, and one cannot compare two things so widely different as the styles of these two generations.  I would think that comparison would still be possible but the question remains whether comparative judgment is possible.  Comparison between things in a very narrow category, for example bathing suit fashions for teens of 2016, makes sense when it comes to fashion, but what about comparison between these things and bathing suit fashions of the 20s?  Does comparison do any good here at all?   Hume just has no way of telling us what makes a class a comparison class where practice and comparison will actually work.  Can you fairly judge fashion from generation to generation?  As T. says of her mom "she cannot compare the fashion statements of today to the ones in her days."  Hume, I think, would require that a good judge try to put his mind into the framework of the age under consideration:  in this case, the mom, to be a good judge, must try to put her mind into the point of the of the person designing the "crop top" or the girls who are using it rather than simply criticizing it out of hand because it seems too revealing based on taste preferences that go back to her own teen years. 
Or is this one of those cases where the difference is "innocent" on Hume's view.  He does allow for differences between generations and countries.