"Then Pharaoh sent and called Joseph, and they brought him quickly out of the dungeon; and he shaved, changed his clothing, and came to Pharaoh." (Genesis 41:14)

Most of us know the Old Testament story of Joseph.  Despite being hated by his brothers, being sold into slavery and being surrounded by the Egyptian culture, he remained faithful to God, working hard and becoming the most trusted servant of the king under Pharaoh.  Joseph was sold to Potiphar, an officer of Pharaoh and captain of the guard. Potiphar's wife wanted Joseph to indulge in adultery but he refused to sin. Through her false accusation, Joseph was thrown in the king's prison for several years. 
 

Prisons were very unhealthy places overrun with rats and vermin like bedbugs, lice, and worse. They lacked hygiene facilities so there was no way to bathe or keep one's physical body clean, much less wash one's clothing. Dungeons were places also called cistern-pits inside the prison so they would have been windowless with perhaps even worse conditions than the rest of the prison's physical layout. Joseph continued to remain faithful to God, was blessed for it, and came to be fully trusted by the prison "warden" despite having to dwell in unspeakably filthy conditions.

When Pharaoh heard Joseph could interpret dreams he called for him and Joseph was quickly brought out of the dungeon. By then he must have looked more animal than human and smelled truly repulsive, on the surface, to others! The Bible says Joseph shaved and changed his clothing before he came to the highest ruling authority in the land. Joseph's earthly master would have gagged and turned away from him had he not "cleaned up." Once Joseph had changed his wardrobe, he was free to enter into the accepting presence of the king.

Indulging in sin makes us appear disgusting and odious (we stink!) to God. While those of us who came out of the world were "dressed" in sin, before we "cleaned up," repented and were baptized, we were barred from spiritually appearing before the Supreme Authority, God. When we obey the gospel invitation and are baptized, we exchange revolting, odious, and filthy rags of sin for brand new spiritual clothing. Jesus taught that inner cleanliness is better than outward in  Matthew 23:25-28 when He denounced the scribes and Pharisees.

The prison Joseph had to live in offered nothing with which he could stay physically clean but Christians have the "running water" of Christ's blood that can keep us spiritually clean when we repent, confess any sins, and ask forgiveness of them through Christ.

"...but if we walk in the light as He Himself is in the light, we have fellowship with one another and the blood of Jesus His Son cleanses us from all sin....If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness" (1 Jn. 1:7, 9)