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.
(..) - Starling? - Yeah. I'm still here, sir. I just... I don't know how to feel about this. You don't have to feel any way about it. Lecter did it to amuse himself. Look, I know it got ugly today, but you mentioned a name at the end: Mofet. Any follow-up on her? Lecter altered or destroyed (..)1991 The Silence of the Lambs
(..) - Miggs, you stupid fuck! - I'm gonna kill him! - Agent Starling! Come back! Agent Starling! Agent Starling! I would not have had that happen to you. - Discourtesy is unspeakably ugly. - Then do this test. No, but I'll give you a chance for what you love most. - And what is that? (..)1991 The Silence of the Lambs