I'm sure if you are able to read this, you understand the job of soap. However, have you ever thought about how it does its job? Soap attracts dirt and breaks the surface tension of water allowing it to stick to surfaces and rinse away the offending material.

With this basic understanding, you can see why leaving soap behind when cleaning a spot on the floor will lead to an even bigger spot in the near future. It is important to rinse the location thouroughly.

Have you considered plain old hot water for the spot? I find that many small spots are caused by my kids spilling juice or water and the dirt from our shoes is then attracted to the location. Most of the time, using a bit of hot water and a cloth, followed by time to dry will get rid of the spot. Using hot water is much greener for the environment than chemicals and is a good first choice.

For tougher spots, I add a little rubbing alcohol to the hot water. The alcohol breaks the surface tension of the water, making it penetrate the spot and then it evaporates quickly leaving no residue to attract new dirt.

As a last resort, I use soap in the cleaning water. However, I make the solution weak and I rinse it well.

Next time you need to clean a spot, consider wheather or not it really calls for a chemical attack.