an 'ugly duckling' that has become a beautiful swan [=an ugly/unsuccessful person or thing that has become beautiful/successful]
('informal') That dog of yours is '(as) ugly as sin'. [=very ugly]
The house is an 'ugly duckling', but it has a lot of potential.
(..) You'll be messing yourself soon enough. Somebody stole my necklace. OK, Mrs Hollister, I'll be right with you. Go on back upstairs. You are as ugly as an old pot, but you still a child of God. Queenie, she won't go take a bath without you. Mercy... I'll be right there! You just wait right (..)2008 The Curious Case of Benjamin Button