I don't think a house would have to be unusual for it to be sold privately, we sold our last house privately and it was because of the fact that these houses were so popular and we knew that we would have no trouble selling it that we advertised privately. It was 18 years ago, so things may have changed, but we had two people view the house, the first couple looked around and asked how much would we drop the price by and the second viewer was a single man who made an offer the next day and proceeded to complete in a very timely manner.