Carbuncular

This word doesn’t actually exist: rather, it’s an invented form of the word “carbuncle,” which is a cluster of boils or infections.

Why I Looked It Up

In 100 Essential Things You Didn't Know You Didn't Know about Math and the Arts, there’s a discussion of “The Gherkin,” which is an oddly shaped skyscraper in London:

Prince Charles sees it as a rash of carbuncular towers on the face of London.

Charles clearly didn’t like it, and it turns out that he’s used the word to describe architecture before. He called a new extension to the National Gallery:

a monstrous carbuncle on the face of a much-loved and elegant friend

The BBC even has an article where they refer to Charles’s “list of carbuncles.”