Selling a home that has a weird smell.
Smell is one of the senses that will either help or severely hurt a selling process. If you have a home that you want to sell or you're a realtor that sells homes frequently smelling the home before walkthroughs can be detrimental. That's why home-baked cookies can help drive the sale of the house, by making it smell great and welcoming.
A dirty toilet is a visible eyesore that would put me off on buying a house. During the selling and buying process of a house anything that can make people remember the house is a great thing, you don't want that memory to be of a used and uncleaned toilet.