A business cleaning service business is a business with great promise to make good money. It's a business that requires hard work and the ability to manage others. You will have a hard time getting good competent workers that will be responsible and do their job in a sufficient manner. The ability to grow this business is unlimited and therefore the profit is unlimited. But the time and work may not be a business for all. If you are hard working and willing to keep on top of things business cleaning service can make you money.
The business cleaning service business is better than a home cleaning business but it has some of the same problems. Good workers are hard to find and managing them is difficult. This business can be good for certain people but it's not a business I would consider to be very good for most. Unless you have a special desire for a cleaning business leave it to others.
A difficulty part would be to actually get jobs. You will need to contact businesses and offer your services. the problem is many already have someone doing their cleaning. If they aren't satisfied with whom they use you will get an opportunity to be given a chance. It will be too costly to advertise your business cleaning service so you will need to pound the pavement, meaning you will need to visit potential customers. Word of mouth will help. Many people you know may very well have a business that needs to hire someone to clean their office. Ask around and make it known what you can do.