Concrete floors are incredibly hard and durable floors. You must also remember that concrete is a porous surface, in which mold, bacteria, dirt, stains from liquids can make the surface unsightly and dirty. This is why you need to have your concrete floors cleaned through a regular maintenance program and even sealed in to keep your floor looking great.
Professional high-pressure deep cleaning is recommended once or twice a year. Straight water will not cut dirt, grime and oils from the concrete floor, this is where professional cleaning solutions can lift and and suspend the contaminants from the surface so they can be removed.
Applying a water based acrylic sealer will darken the concrete, and give the floor a slight gloss, this system is an expensive way to preserve your concrete floors so they can last a long time.