I think mini judges long ago got used to seeing dark brown bays and beige chestnuts, especially in spring time. You and I may prefer their unclipped color but the judges definitely want to see them clipped!
Jill and Kay are both right- the later in the season it is, the better their color will be regardless of how many times you've clipped and the more you clip early in the season the better their color starts to come back in. Last year was my first year of owning my own Double K's and I was surprised how much faster his color came back with more clipping. I had to allow a month after the Oster clippers I was renting and only a week after a clip with the Double K's.
You've got a very nice little chestnut there!
Leia