My idea for a change to the real estate listings for "used" houses:
You can sell your house back to the game for a 20% loss and immediate cash (the way it is now), or
Since you're made improvements to the place; added trees, piggies, butterflies, milkers, etc, you list a price you think is fair and wait for it to sell to a buyer.
If you sell the house back to the game, it immediately reverts back to "new" condition (no animals, unless a baby chick came with the place, etc) for the original selling price.
If you list the house for sale, you can purchase one additional house to live in (which would then exclude you from access to the old house - no living out of two houses by listing an exorbitant listing fee). After two weeks, if the house hasn't sold, the game purchases your old house at the 20% loss and reverts to "new" condition, thus not tying up tons of real estate.