I wonder how they know?
The dog we have that is "sensitive" this way did have a weird life experience. Her owner was a cancer victim who died alone at home. No one knew and the dogs were found STARVING a month later by the neighbors when they wondered what was happening. She became strangely attached to my hubby the moment she saw him, I figure she replaced the dead person in her mind with Hubby. So she "worries" about ill people. She knows they might never move again.