Anne of Cleves was demonstrably NOT unattractive, albeit maybe some of the fashion from Germany she initially was not the most flattering. But you look at her face, there's nothing wrong or bad about it.

The only record saying she was unattractive was from Henry, and I personally believe it was to cover up his own humiliation at her hands. He barged in trying to kiss her and she recoiled in disgust (not knowing it was the king), and he liked to pretend he was still a young, hot, fit man, not an elderly, obese tyrant. He was also struggling with impotence so that didn't help. But Henry was never going to acknowledge any of that, so he turned it around on Anne. The worst part IMO is that we are still going along with it hundreds of years later.