We have a "nun" living upstairs. She has been here for 18 years, is an artist, is single, and teaches Sunday School. You should see what she had done to my yard. Stone walkways, stone walls around the flower beds, lots of plants and wild flowers, and snow sculptures in the winter. She's a regular Michelangelo with snow. We don't really make a profit from the rent she pays, but it covers our taxes and insurance.
But I've had a few bad ones, too. Holes in the walls, bleach on the carpet where they tried to clean up candle wax, and a few things walked away from my garage when they left.
All in all, I've been very happy that I made my upstairs into an apartment. We don't need all of this big old farm house.