Why Do I Have to Take a Bath?

"Why do I have to take a bath?  I'm going to get dirty again." 
"Why do I have to brush my teeth?  I'm going to eat again"
"Why do I have to brush my hair? I'm going to mess it up again."
"Efficiency is better than hygiene."

Notes:
Many routine, daily personal habits are expressed with reflexive verbs in Spanish:  bañarse, ducharse, cepillarse, peinarse, etc.  The reflexive pronoun is required.
des- is a convenient cognate prefix: peinar/despeinar, hacer/deshacer, etc.