As a vaguely related aside, my skin is typically better when I have a decent vitamin c intake. Essentially all I do is have a orange or two every night. Nothing too extreme.
Oranges are not particularly high in ascorbic acid as such things go, so I would expect any effect to be pretty marginal. Other fruits and vegetables contain considerably more.
They are, but you have to eat the peel, too. I actually love it, but it’s not to everyone’s taste. Of course the oranges need to be free of pesticides, peel declared suitable for consumption.
This is VERY anecdotal!