I personally don’t like high pony tails. They tend to cover girls faces when they turn and it looks messy. Low ponytails I really like when the dress is not busy. If the dress has a lot of details I prefer the simple bun.
I can of course not answer the question on behalf of all judges, but in my experience most judges don’t mind as long as the look is suitable for the person and the style/character of the dance and does not disturb the overall picture i.e. so long that it is going in the face of the person or the partner. Furthermore, I would like to stress that we as judges always judge the dancing and the appearance can only slightly influence the overall opinion.
From a personal point of view, I’m not a great fan off high long hair ponytails on girls. I feel like the hair covers the face and I love seeing the girls’ eyes. I also feel it’s always in your partner’s eyes and sometimes mouth. Which I’m sure is not very pleasant and could be very distracting.