I wonder how long you showed up after the owner left. Perhaps he left a few days food in anticipation of you being late. That would explain a lot of the feces and the partial dehydration. An unfriendly dog is not very unusual if you have never met. I bet after you feed the dog a few times it will warm up to you.
Bedding gets a little thin if the house floor is slatted and the worn straw falls through.
It is not winter yet and bedding is mainly for comfort and not warmth in the off season. Most dogs don t go in their house much in the summer and would rather lay in the dirt. out side. My girl has an impeccable backyard with a shady lawn and mulch and the dogs would rather lie on the dusty dirt pile I excavated for a remodel.