A Scout is clean in thought, word and deed. He uses clean language. He speaks good of others. He is well-kept in appearance. He is morally straight.
President Gordon B. Hinckley’s specifically spent many words to describe his third “Be Attitude” — be clean.
He warns of the destructive power of pornography, and degrading entertainment:
We live in a world that is filled with filth and sleaze, a world that reeks of evil. It is all around us. It is on the television screen. It is at the movies. It is in the popular literature. It is on the Internet. You can’t afford to watch it, my dear friends. You cannot afford to let that filthy poison touch you. Stay away from it. Avoid it. You can’t rent videos and watch them as they portray degrading things. You young men who hold the priesthood of God cannot mix this filth with the holy priesthood… 
And while I speak of such matters I want to give emphasis again to the matter of pornography…Stay away from it. It is exciting, but it will destroy you. It will warp your senses. It will build within you an appetite that you will do anything to appease. 
He also spoke about keeping ones language clean:
Avoid evil talk. Do not take the name of the Lord in vain. From the thunders of Sinai the finger of the Lord wrote on tablets of stone, “Thou shalt not take the name of the Lord thy God in vain” (Ex. 20:7).
It is not a mark of manhood to carelessly use the name of the Almighty or His Beloved Son in a vain and flippant way, as many are prone to do. 
He encourages a clean body, inside and out:
What creation is more magnificent than the human body? What a wondrous thing it is as the crowning work of the Almighty…
How handsome is a young man who is well groomed. He is a son of God, deemed worthy of holding the holy priesthood of God. He does not need tattoos or earrings on or in his body. 
He taught about the hurt and regret that can come from falling to moral temptation:
You young men who plan to go on missions must recognize that sexual sin may keep you from that opportunity. You may think that you can hide it. Long experience has shown that you cannot. To serve an effective mission you must have the Spirit of the Lord, and truth withheld does not mix with that Spirit. Sooner or later you will feel compelled to confess your earlier transgressions. Well did Sir Galahad say, “My strength is as the strength of ten, because my heart is pure” (Alfred, Lord Tennyson, Sir Galahad , st. 1).
My dear young friends, in matters of sex you know what is right. You know when you are walking on dangerous ground, when it is so easy to stumble and slide into the pit of transgression. I plead with you to be careful, to stand safely back from the cliff of sin over which it is so easy to fall. Keep yourselves clean from the dark and disappointing evil of sexual transgression. Walk in the sunlight of that peace which comes from obedience to the commandments of the Lord. 
When a young man is clean in all of these circumstances, he has the right and privilege of the Holy Ghost as a constant companion. A clean Scout will avoid harmful habits, ill-speaking, moral transgressions and ultimately regrets of past sins.
A Scout is Clean, but He’s Not Afraid to Get Dirty!
While this can be a very heavy subject of purity, let’s not forget what Scouting is all about — good, messy, fun!
Check out this speech given by Eagle Scout Mike Rowe, host of the Discovery Channel series Dirty Jobs and defender of dirt, at the 2010 National Jamboree where he presents how he agrees that a Scout is clean, but he add has his own twist on the statement.
These Scouts took Rowe’s suggestion seriously, and decided to get a little “dirty” at the 2013 National Jamboree.
On the second day of Christmas, a Scout remembers to always be clean. He strives to be clean in thought, word and deed.
Author: Melany Gardner | Marketing & Program Assistant, Utah National Parks Council
Reference 1 – 5. See President Gordon B. Hinckley, “ A Prophet’s Counsel and Prayer for Youth.” (2001, Jan.). LDS.org.