Green’s Dictionary of Slang

1. a very unattractive or unappealing person, sight or situation; the number can differ, but is commonly forty...; often in phr. look like...

1922		Courier-Jrnl (Louisville, KY) 19 May 6/8: Speaking of a very homely girl a youngster recently said, ‘She looks like seven miles of bad road’.
1935		‘Ella Cinders’ in Montana Butte Standard (MT) 1 Feb. 23: [cartoon] Do I have to stand here, looking like five miles of bad road, while you play questions and answers?
1941		‘Freckles & Her Friends’ in Indiana Gaz. 24 Jan. 10: [cartoon] If she’s a good looker, I’ll follow the flowers later myself. Okay! And if her face is like four miles of bad road I’ll just let her down easy.
1959		Duane Eddy [instrumental title] Forty Miles of Bad Road.
1969		S. Greenlee Spook who Sat by the Door (1972) 103: I’ll take care of your old lady [...] The one looks like twenty miles of bad road.
1977		(con. 1969) M. Herr Dispatches 28: You only look like about ten thousand miles of bad road.
1989		P. Munro Sl. U. 123: Like five miles of bad road like something really awful.
1998		T. Sanders ‘Operation Fishhook’ in Jack mag. II:2 🌐 ‘You look like forty miles of bad road, Tui. You’ll need to see a doctor, and you’re probably gonna have a few scars.’ Tui winced as Zeke probed a wound with forceps.
2005		M.B. ‘Chopper’ Read Chopper 4 255: He’s got a face like five miles of bad road.

2. a phr. describing one who is completely exhausted; often in phr. look like...

1986		C. Stroud Close Pursuit (1988) 91: Kennedy. You been on since six this morning. You look like forty miles of bad road.
2003		D. Belton Underground Asylum 228: ‘You look like you just drove forty miles of bad road.’ ‘Yeah, I’m beat.’.