Six years ago, I had a listing on Central Park South that was a beautiful park view apartment. There was just one little problem: The pigeons nesting on the balustrades outside the living room window. I could not sell that place because nobody could see past the pigeon poop.

Eventually, with the help of the super and some artfully laid sticky bird gel (pigeons apparently don't like it when their feet get sticky), we persuaded the pigeons to move on. As soon as they relocated, the apartment sold (well).