How old do you prefer your feet--young and fresh, or older and more "seasoned?"
And when I say "young," I mean 18, or older!
I prefer the feet of older women--30's, 40's, 50's. I feel that their "maturity" adds something to them.
I once read a statement in a women's magazine: "The body part least likely to reveal a women's age is her feet." I agree!

I went for young, since college age seems to be the best time for women to experiment with things like not wearing shoes. I feel like as they get older, the shoes come back on.

If the owner of the feet is good looking, and if her feet are OK.. I don't care that much about age.
Generally I am not that much into girls who are younger than 20, and in ladies who are older than 55.. but some teenagers and some cougars..
are absolutely worth an exception..

Age doesn't matter IMO. But I went 25-35 as that's the age (allegedly) women start to properly grow up, making the barefoot thing more unique - plus that's the range I'm in myself right now.

Hell the OP should have made "middle" 25-45 tbh, as I'd take a 40 something with amazing feet over a 20 yo with gnarled toes and bunions. E.g:

https://www.wikifeet.com/Monica_Bellucci
https://www.wikifeet.com/Liv_Tyler
and of course: https://www.wikifeet.com/Julia_Roberts

Of course, Julia Roberts is well-known as a regular barefooter, and Liv Tyler's arch is un-fucking-believable. Above average size and a perfect heel for cupping and kissing.

I chose "middle". You know, young people do crazy things that´s why if you see a young girl walking barefoot, it doesn´t strike you as something that odd. On the other hand, a woman in her mid-thiries is something quite different. At that age you´re supposed to behave in a respectful way and violating this "rule" by kicking your shoes off in public and showing your dirty soles makes the whole situation far sexier. As for women in their forties and above, well it really depends. They sometimes want to look younger than they really are and if they overdo it, it can be pretty off-putting.

Yes, perhaps I should have made it 25-45.
I agree, seeing an older lady barefooted in public is an unusual and special sight.
The French actress Brigitte Bardot is now in her 80's--and I hear tell that she still loves to go barefooted!