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.
(..) - Sure, yeah. - Great. Where do you want me? Over here? Yeah, that's great. Don't make me look ugly. That's impossible. Perfect. - Is that good? - Great. That's great. (..)2002 Spider-Man