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.
(..) So did you. I had to pick a side, George. It was an aesthetic choice as much as a moral one. And the West has become so very ugly. Don't you think? Did Karla ever consider having you take over the Circus? I'm not his bloody office boy! What are you, then, Bill? (..)2011 Tinker Tailor Soldier Spy