high quality saddle leather is an amazing thing -- it takes a lot , but with proper care turns becomes more and more beautiful with age. saddles and bridlery get sat on, covered with numerous substances (including water, sweat -- both equine and human -- mud, dander, dust, horse slobber), tossed around, rubbed, jostled and generally put through the wringer. which is not to say one should abuse tack, but its intended use necessarily brings with it a bit of a tough life. at the end of the day's equine activities the tack is cleaned with saddle soap and water, every few weeks it is conditioned, and a couple times a year oiled.
as it's used the leather will develop scratches, dark patches and other marks -- but with constant use and cleaning they develop a deep, glowing burnished finish from all that friction. they've just got to go through an initial ugly duck phase to turn into swans. since barenia is a saddle leather i'd imagine that this applies to it as well -- though because of the tanning in oil process i don't think it would ever require conditioning or oiling. if i had a barenia piece i'd just rub it down every couple days with a very slightly damp cloth. and ignore the marks and such until they start to turn into a patina, as HG describes with the grease stain.