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.
(..) river, what a waste of time! Cut us down Beith. I have gold I can pay you. It is not here, it's hidden back in the woods. Shut your ugly mug Huntsman. If you had any pennies you'd have pissed it away on mead by now. - Cut us down and I'll show you. - You lying dangler. (..)2012 Snow White and the Huntsman