Ian Ground at the Times Literary Supplement:
Central to what is known as the “paradox of the ugly” is that ugliness does not just repel but also invites fascination and (prima facie at least) aesthetic appreciation. Thus the blobfish, the no doubt proud recipient of the ugliest animal award, the goblin shark and the naked mole rat hold – and in an as yet unexplained sense, reward – our attention. Deformity and injury – for all the moral problems that swirl around our reactions – excite a morbid fascination. And, of course, countless artworks and traditions have long enlisted negative responses to the revolting, disgusting, horrific and abject in pursuit of their positive goals.
Three strategies can go some way to sidestepping the sense of paradox. First, we may say that the paradox arises because of a failure to distinguish between the aesthetically and the artistically valuable. The ugly may be put to beautiful artistic purpose. But in such cases it could be that the aesthetically bad may be artistically good. For example, it would be intelligible to say of Francis Bacon’s “Screaming Pope” that the painting is insufficiently ugly. The ugly may be beautifully represented by the artist.
Second, we may say that the ugly is the vehicle for the appreciation of certain thoughts and feelings that could not otherwise be expressed. It might be the vehicle for cognitive value, for instance, in the traditional artistic duty of holding up a mirror to its audience. Third, we may say that the delight we take in the ugly is a parasitic response to the norm.
more here.