It is incredibly rare that I fail to finish a book (I'll persist for several months if necessary) but I only managed 100 pages of this before I threw in the towel.
I'd say that this book fails on at least three tests: structure, content and engagement.
First off, as other have noted there isn't really a theme here. In fact, there isn't even a point; the author seems to think that if she mentions relativism and changing perspectives over time that it is some sort of argument but all you get is a series of examples that sit as islands to one another.
Moreover, while she is constantly going on about relativism she is happy to go on judging views from the past through her own modern lens; why not take older views any less seriously than her own? Yes, she tries to impress a pluralistic contemporary perspective and say that the one you choose is contextually-bound but never questions her own application of that entire viewpoint versus the ones she is ridiculing. Something even approaching a rational argument would have gone a long way here.
Secondly, the author frequently repeats opinions, quotations, etc. as gospel with zero counter point. Thirdly, she conflates different senses of ugly such as ugly people vs ugly behaviour to the extent that she stretching their meaning from them. Theories or approaches like this verge on the realm of crackpot-theories because they attempt to explain everything through the lens of a single idea (in this case ugliness) regardless of how well the fit is.
Moreover, the author often uses the word "conflate" (or some analogue) as if it were an argument in itself standing in no need of justification against her 'bifurcation'.
All in all you get a sense of a book which makes no definite points and meanders aimlessly with regards its subject-matter but, at the same time, is more than happy to spew unargued values and positions at you.
Which bring us to the most fatal problem from a reading perspective: the style is not as engaging as it needs to be. Without clear themes the stylistic issues bog the work down to a crawl as the reader wonders what exactly they are reading it for. Overall, I got the strong feeling that I was reading a PhD thesis- make of that what you will.