LeeVon,
To date I have not loaned out a dog. However there are a handful of people that I would loan a dog to. These people take care of their dogs the way I take care of mine.
I have one dog in my barn that I do not consider to be "my" dog. She is an old brindle cur with more hogs under her belt than I can count. I doubt that money could buy her, but my deal with her "owner" is this. Hunt her until you are done with her, or she dies. They want her back when I am through with her. If the day comes that I no longer need her in my pack, she will go back to them alive. If she dies while in my care, her body will be taken back to them, to be buried with their other "great ones" No hard feelings either way.
IF A DOG LEAVES MY YARD HE'S YOURS TO DO WHAT EVER YOU WANT.
IF A DOG COMES TO MY YARD HE'S MINE TO DO WHAT EVER I WANT.
That policy right there will stop potential BS as long as both parties are aware of that in the beginning.