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.
(..) like a big man, Press firmly, There's three copies, ma'am, - You have a nice day, - Yeah, right, They can be ugly as sin or they can look like Miss America, In this station, once you stop 'em, you write 'em or you cuff 'em, Leave your hormones out of it, young blood, (..)1994 The Glass Shield