Do you have a bathtub in your sim’s house? Send your sim to the grocery store in town and buy one rubber duck and one bottle of bubble bath for every bathtub in the house. The duck doesn’t wear out and the bubbles never run out. When your sim bathes with the duck, she will get a positive moodlet that sticks around for a few hours after every bath.
Your sims will not only get clean in the bath, but they will play with the rubber ducky during the bath, giving them the Duck Time moodlet.
And don’t forget to take a ducky along when you send your sim on vacation. The duck can be placed on a tub on a community lot, used and then put back in your inventory. Your sim is going to take a bath anyway, why not add this little positive to her mood?