For one thing, most thru-hikers never wash their clothes. Hansel and Gretel, typically wash their shirts every 2-3 days. They do laundry whenever they are in a town on their resupply days.
They brush their teeth every day. Hansel is even hiking with a roll of floss. There were only three occasions that they decided to skip a teeth brushing because it was so freezing cold.
Hansel washes his hair every 2-3 days. If they aren't in a town, he uses stream water to clean up. Gretel tends to save her hair washing days for when they are in towns. She just keeps her hair in tight braids so any existing trail grime is well contained. It would be too much primping to wash and re-do her braids every 2 days. Who has time for these things when you need to cover 20 miles before the sun sets?
As you can see in previous pictures, Hansel is clearly letting himself go on the facial hair front. This is probably the closest he will ever get to growing a beard. (He's always been a bit patchy.) Gretel, on the other hand, has been avoiding the hippy-pit look at all costs. As a matter of fact, when they were in Hampton, TN, they could not find a shower anywhere so they used a gas station bathroom to clean up which was complete with an underarm shave. "Yup. That happened," Gretel added over the phone.
Another thing that makes Hansel and Gretel unique is that they actually wash their pots and cups between uses. Apparently other hikers just eat on top of old food. Sounds a little nasty to me!
So as you can see, Hansel and Gretel are keeping things sanitary out in the woods. They actually asked an employee at one AT outfitter how they compared to other thru-hikers. The employee confirmed that they were some of the best smelling hikers he had ever encountered! Three cheers for deodorant!
And some random pictures for your viewing pleasure: