What's more important? Clean hands - or a clean heart? Should we be more concerned with what we put into our bodies - or what comes out of our bodies through our words and actions? Jesus is pretty clear in Matthew 15 that God's is not so much concerned with the raw materials that go into making up our bodies (physical) as He is with what we do with them (spiritual).
The Pharisees are great ones for emphasizing superficiality, focusing on how things "look." To them, it was essential that people wash up before they eat and engage in the tradition of ritual cleanliness. That's how to stay pure and undefiled from the world, they thought.
Yet Jesus has something else in mind entirely. He's not looking superficially - He's looking spiritually. And what He sees are the things that flow out of a person. "Evil intentions, murder, adultery, fornication, theft, false witness, and slander" - these are the things that defile!
"Cleanliness is next to godliness" may make a pithy saying - but the sentiment is to be found nowhere in the Bible.