Using Prestidigitation to get clean means they had to have gotten dirty in the first place.
And, as I said in another post. Elves do blacksmithing. Elves build buildings. Elves hunt. Elves go to war. Elves weave. Elves domesticate animals.
Elves do work. They do hard work.
I view elves as telekinesing and shaping wood, stone, etcetera, to build tree house towns, supertower spires, and floating cities. Elves build by means of magical rituals.
Wood Elves hunt, but similar to Legolas still smell good and look polished while doing it.
Elves weave, especially weave fate, and the fabrics are pristine and precise.
Do elves domesticate animals? I say, no. But elves befriend wild animals, and sometimes shapeshift into wild animals.
Elves do metalwork. And various technologies. But if elves can keep themselves clean in mud, they can probably stay clean while working metal.
Elves go to war. In folkbelief, they only fight be means of magic. Properly, elves are fullcaster mage classes only. But the High Elf Eldritch Knight engages the martial power source in combat. Ancient Paladin is appropriate too. Of course, the elf knight prioritizes combat effectiveness over appearance. Nevertheless, the elf knight has magical ways to stay clean during combat, and to clean up after combat. For example, the elf chain armor of the knight is probably the Mage Armor spell, that appears pristine clean under any circumstance.
Elves do magic. They dont work hard in the same ways that humans work hard. If an elf ever looks unkempt, it is because the elf has an urgent circumstance, or else, the elf is having fun. Occasionally, an elf looks awry because an other elf cursed their fate to look that way, and then the awry elf prioritizes a remedy. Elves are like human actors on movie sets. For the elf, that is who they are.
Looking good and wearing fashionable clothing is an aspect of the charm factor, for the aura of mystery.
The charm and glamor of an elf is their true self, not a role.
I don't see the point in trying to dismiss this
The more one acculturates an elf into human ways of doing things nonmagically, the less elf the elf becomes.
For an elf, magic is the solution to every problem. Magic is fate.