John 13:7-11 NIV
7Jesus replied, "You do not realize now what I am doing, but later you will understand."
8"No," said Peter, "you shall never wash my feet."
Jesus answered, "Unless I wash you, you have no part with me."
9"Then, Lord," Simon Peter replied, "not just my feet but my hands and my head as well!"
10Jesus answered, "A person who has had a bath needs only to wash his feet; his whole body is clean. And you are clean, though not every one of you." 11For he knew who was going to betray him, and that was why he said not every one was clean.
Jesus had touched and washed Judas' feet, but He was not able to touch his heart. Judas would not receive the cleansing bath of God's mercy and grace the others had received. It was offered, but refused.
One can be completely clean in the eyes of the Lord, yet still have dirty feet, for now we are still in the flesh and the world.