YES. If my horse was kept in those conditions I would be moving him out immediately and taking down evidence of neglect. If anything, it is horse neglect first and barn second. Planks can be replaced, water buckets can be scrubbed, but it will take a little more to get rid of a nasty hoof abscess or a hazardous digestive system sickness. Also, when horses are kept in their own waste they start to inhale the methane and ammonia and they weaken. Horses that are over-fed can stress out their joints, endanger their heart health, and founder. Absolutely, such living conditions are unacceptable.
"The trouble with the world is that the stupid are certain and the intelligent are full of doubt"