Nice. The horns *are* semi-cool, the bag is a bit "sophisticated, "true, but resembles an original that was discussed elsewhere on this forum a few months back. The coat is cool, too. I have one somewhat similar that my wife sewed for me about 10 years ago. It is made of braintan deer, and yes it did get somewhat dirty. Actually it got black grease on it. I wiped off the grease as best as I could, scraped the exterior of the skin, and found some desert dirt to rub into it, that just about matched the color of the coat.
I have always heard, but have never tried this, that DRY corn meal rubbed onto the dirty spot on buckskin will clean it. Seems like it might be worth a try--the worst that might happen is you get some dirty corn meal.
HTH --JB