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.
(..) I was alone in a room with a naked girl, but... - Didn't know where to put it? - I know where to put it. Was she... old and ugly? Young and gorgeous. A whore named Ros. What color hair? - Red. - Oh, I like red hair. (..)2011 TvShow: Game of Thrones Title: Cripples, Bastards, and Broken Things Season: 1 Episode 4