When I was in third grade we moved into this huge house in upstate NY. The former owner died in the house. I would hear sounds of someone walking up and down the stairs, taking a bath, lights would go on and off, and shades would go up and down. I was never frightened. It never felt like an entity was there.
When my grandmother died we cleared out her home and had two estate sales. She did not die in her home. She spent two months dying in that home, however, of a brain tumor caused by metastasized lung cancer. She coughed and coughed and coughed and coughed. It was a vicious, endless cough. A young woman and her husband and baby came to one of the estate sales. They were interested in a specific item and were asking my mom about it when the young woman became startled and asked if anyone else was in the house. We said no, it was just the two of us, why? The young woman said she could hear someone coughing and coughing and coughing. She got so freaked out that she left (though they did come back and purchase the item they were interested in buying at a later time).
It seems to me that there are no real ghosts, just echoes of what used to be.