Because these birds have grown excessively dependent on the food commonly available in urban areas, they have also developed the habit of continuously moving around in search for places where food can be available. This mobility also spreads their guano is an eight to ten hour flight radius. But that is not really the main problem, the real threat with pigeons habituation is that they have the tendencies to stay in an area (without moving) for as long as 16 hours! Imagine the amount of guano that hundreds of pigeons can leave in an area after staying for that long.
Types of External Soiling
The damage that their droppings can do also varies depending on how these droppings are left in the first place. For example, if the droppings are due to daytime perching, the damage would seem random and irregular. That is, a larger area of the building will show visible damages. One can be sure that the soiling is caused by overnight roosting when the damage is concentrated in a specific area. That is, all the other areas surrounding the soiled area do not exhibit signs of soiling. These two types of external soiling also depends different approaches in cleaning.

Although it is really troublesome to have such soils caused by pigeons, the soils are also very good indications of where the anti-perching products should be placed. This means that the pigeons will not be able to give you any worries anymore because they have given out themselves which area in your building they like to perch the most, thus you will know which area needs anti-perching products. You don't have to worry about pigeons just finding a new site in your building (one with no anti-perching products) because pigeons are most inclined to stay on one breeding or roosting area alone. If their roosting area in your building is no longer available, they will find a new building instead of finding a new area in your building.
Special Considerations
Despite being pests, you still need to apply special considerations to pigeons most especially if you find a nest in the area where pigeon chicks are present. These birds are still very weak to make it on their own and there are laws that protect such helpless birds. If ever you find such chicks (also called pigeon squabs) while you are cleaning, you might want to set aside these birds first (maybe place then is a container and keep them safe for a while as you do your cleaning). Then, it is wise if you call the Department of the Environment, Food and Rural Affairs or DEFRA office to report about the squabs. After informing their office, you will either be advised to take the squabs or the eggs to them or to a wildlife rehabilitator. From there, these professionals will handle the birds and you will be free of the responsibility.
Cleaning Operandi
Remember that guano is a good habitat for bacteria and viruses. If you are not careful enough, you

However, for small quantities of wet droppings, a hot soapy water solution would be enough to clean out the guano. When pigeon guano is wet, it becomes less threatening to human health and so there is no need for you to buy disinfecting agents to be extra sure. The soapy water solution can be used to splash out the guano from the surface before scrubbing.
Well-dried guanos have to be treated differently. Like what has been said earlier, guano becomes very conducive for bacteria habitation if it is dry. Thus, for such cases, it is important that you use the right equipment rather than simply cleaning with your hands. For example, use a paint scraper (of course wear gloves) to remove well-dried guano that stick on the windowsills and the other architectural features of your house or building. If the guano is too difficult to scrap off, you may spray the guano with enough water to make it softer. After removing these dried guanos, simply wash the area with hot soapy water.