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.
(..) with the problem, okay? It's the world that seems to have a problem with me. People take one look at me and go, ''Aah! Help! Run! A big, stupid, ugly ogre!'' Theyjudge me before they even know me. That's why I'm better offalone. You know what? When we met, I didn't thinkyou was just a big, stupid, ugly ogre. Yeah, I know. So, uh, are there any donkeys up there? Well, there's, um, Gabby, the Small and Annoying. (..)2001 Shrek