“So clean you could eat off the floor.”
[of a room or a house] very clean. Her kitchen is so clean you could eat off the floor! It’s so clean here you could eat off the floor. I prefer a little mess, myself.
See also: clean, could, eat, floor
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
But eat Marmite off the road?