as ugly as sin

(as) ugly as sin

Extremely visually displeasing or unattractive. I wouldn't buy that painting, it's as ugly as sin. I'm sure I looked ugly as sin, with my makeup smeared all over and my hair a total mess.
See also: sin, ugly

(as) ugly as sin

mod. very ugly. This car’s as ugly as sin, but it’s cheap and dependable.
See also: sin, ugly